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Are Rotating Powerheads Any Good?

March 9, 2009

There are several important factors that should be present if a marine aquarium is to be a success. In both fish only and reef aquariums seawater movement is one of them.

One reason for the importance of movement is oxygen intake, if it is adequate the seawater will constantly reach air/water interfaces, in particular the display aquarium surface, where gas exchange can take place. Another reason is that it assists corals obtain food and rid themselves of mucus.

There are several ways of providing adequate movement, some advanced and some ‘basic’. It is likely that many (most?) aquarists use ‘basic’ equipment, namely powerheads. These devices are available in more than one type, though they are all basically an electric motor made seawater safe by encapsulating it in resin, the motor drives an impellor, and there is a seawater intake and outlet. The powerheads could be narrow outlet or wide (‘soft’) outlet types. The wide outlet ones are able to move large quantities of seawater but because they push out the seawater on a wide front the impact is soft and not harmful to corals, particularly if there are two in opposition or they are timed. Narrow outlet powerheads pump a much thinner stream of seawater which is very linear and can damage fairly close corals because of the force.

Random and chaotic seawater movement is the aim and this is often obtained by placing powerheads in opposition to each other and also ‘bouncing’ the outlets off the glass. This should result in the desired seawater flow once a bit of trial and error with powerhead positioning has been completed.

With the narrow outlet powerheads there is a further option and this is to use the generated flow of the seawater to drive a mobile directional outlet. This type of outlet can be bought as an ‘add on’ or alternatively a powerhead obtained which has the required outlet fitted. What happens is that the flow of the seawater from the powerhead causes the outlet to swivel from side to side in an arc. The movement of the outlet is not particularly fast and when the end of the arc is reached the direction is reversed. Another method is an outlet that spins, the seawater acting something like jet propulsion driving it round.

This idea has merits. The seawater flow is automatically being re-directed continuously which is good and in itself is going to create varying currents in the aquarium. If there are two powerheads present, for example, and each has a rotation ability then continuously varying seawater flow will be generated at each end of the aquarium. In addition, from time to time the outlets will come into direct opposition to each other and create more random currents.

Of course there have to be disadvantages! First of all, the rotation is driven by the outlet from the powerhead which detracts from the strength of the flow, though this could be compensated for by the powerhead strength itself. The rotation mechanism is submerged in seawater and there is the possibility (probability?) that the rotation will slow down or cease because of calcareous build up. Also, the seawater from the outlet is still linear even though it is rotating, though it would hit a coral that is in the way X number of times per minute rather than continuously. Standard powerheads require their outlet strength checking from time to time and in addition the rotating powerhead needs checking to ensure the rotation mechanism is operating correctly, meaning there is a small addition to routine maintenance checks.

Rotating powerheads are a useful idea and I have nothing against them. However, and this is purely personal, I prefer standard powerheads that have been correctly sized and placed. Better in a suitable aquarium would be wide or ‘soft’ outlet powerheads in opposition, or timed.

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Can You Have Too Much Seawater Movement?

March 3, 2009

Seawater movement in a marine aquarium, whether it is a fish only or reef system, is important for the overall health of the environment.

Adequate movement allows for oxygen intake at air/water interfaces, particularly the surface of the display aquarium. A high level of oxygen in the seawater is obviously good for fish and also for corals. The movement also helps corals shed mucus and brings food to them.

Is it possible to have too much movement? It is.

Generally, fish are well adapted to strong movement; their real home is the wild reef. Dependant on their position on the reef they are able to deal with all sorts of movement from chaotic to wave even to linear all at various strengths. The general guideline for seawater movement in a fish only system is 10 times the net gallonage of the display aquarium (the sump, if any, is ignored). This is easily achieved by sizing powerheads etc correctly.

A reef aquarium could be soft or hard (SPS) corals or a mixture. The general guideline for movement in a soft coral aquarium is the same as a fish only one. The requirement for a hard (SPS) coral reef is considerably higher, here the general guideline is 20 + times the net gallonage of the display aquarium. Again, this can be easily achieved.

Seawater movement in a mixed hard/soft coral reef usually caters for the SPS corals. Any soft corals are carefully chosen and placed so that they receive less movement. Low down on the reef is usually the place for them.

If the system includes a sump what seawater movement is required in that? In this case the general guideline is about 3 times the total system net gallonage per hour. The flow usually relies on a gravity feed at the ‘in’ end and a return pump at the other. This creates a straight through or linear flow. In a sump this doesn’t matter.

As is often said the flow type in the display aquarium should be random and chaotic. This is achieved by, for example, playing with the positions of the powerheads.

So what if the aquarist has made a mistake and has oversized the return pump in the sump? In this case livestock, apart from maybe algae, are unlikely to be affected. However, there is the possibility that if a deep sand bed (DSB) is in the sump the very fine sand is going to be taken from one end of the sump to the other, though many aquarists use baffles to prevent this. It would take considerable over sizing to create a real problem.

In a soft coral reef care is needed with water movement. If the movement is too strong then some of the corals will bend over like trees in a gale or worse. Fine sand from a DSB will blow about and land on rock decorations and the interference with the DSB will reduce or spoil its filtration action. Even decorative sand, which is coarse, could blow about.

With the SPS reef the corals demand more seawater movement and the likelihood of an excess is lower. As said, the guideline is 20+. In this type of system close attention needs to be paid to the type of sand used for the display, a DSB would be better off in the sump and decorative sand is likely to shift about. Close attention also needs to be given to the position of any soft corals.

What of the fish? With an SPS reef where the aquarist has provided very high seawater movement it is necessary to have fish which are able to deal with that movement. Some fish would not be suitable. Having said that, there are always fish that dwell around the rocks, and anyway the seawater current strength is not aquarium wide, such as parts close to and within the reef.

A very severely ‘over pumped’ display aquarium generates the vision of fish going round in circles as though in a washing machine, all looking most puzzled, and soft corals lifted from their anchorage and mashed by impellors! That’s not going to happen.

It is possible to provide excessive circulation. Aquarists generally consider livestock when thinking of circulation and this is of course quite correct. In addition though consider other aspects of the display such as sand. These decisions should preferably be made at the design stage.

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Closed Loop Water Circulation

January 14, 2009

As with many things in this hobby closed loop circulation is a subject matter which can be quite confusing. This topic has been briefly covered before however in this article I hope to cover this area in more detail.

Water circulation in an aquarium, especially a reef aquarium where closed loop circulation is more suited for is exceptionally beneficial. I rate water circulation as third in a list of must haves – the two above it are water quality and lighting. Water circulation by many is actually classed within the water quality area however I prefer to keep it separate.

Water circulation within a reef aquarium is important for many reasons. It allows for food to be provided to corals, waste to be removed from corals, oxygenation of the water at the air interface, delivery of water to live rock as well as making the aquarium a more natural habitat for the aquarium inhabitants.

There are many ways for the aquarists to provide water circulation of which the closed loop method is just one.

So what is closed loop circulation, what are the benefits and how does it work?

The easiest way to describe closed loop is using an external canister filter as an example. With an external canister file there is in inlet pipe which delivers water to the filter. The canister filter pump then pushes the water through the filter and it is delivered back to the aquarium via a single outlet.

Closed loop circulation is exactly the same as this with the exceptions that there is no filtration involved and that the water velocity is greater.

Sounds very simple and in reality it is. With a closed loop the water inlet to the pump (which is located externally to the aquarium) is located underwater as is the outlet so effectively you have a ‘closed loop’ of pipe work which is connected to an external pump.

The inlet, pump and outlet when connected together are known as a loop

What happens is that water flows down the inlet to the water pump. When the pump is switched on water is forced up the outlet pipe and out into the aquarium. With water being pushed up the pipe water is drawn down the inlet pipe and the cycle continues.

In this type of system normally one pump is used per loop however one loop can contain numerous outlets. For example the inlet is under water in the aquarium. Water is provided to the pump which, when turned on pushed water back up into the aquarium. As the pumps output is connected to pipe work this is run up to the aquarium and then inside the aquarium. Once in the aquarium there is a run of pipe which can be located anywhere in the aquarium as long as the outlet(s) are under water. It is normally recommended that a loop has no more than 3 outlets however it does need to be noted that the more outlets the loop has the more the power of the water force will reduce. Therefore from one loop you could have three outlets which can be located in different areas of the aquarium, therefore providing more areas of flow from one pump.

So why would anyone consider using more than one loop? This depends realistically upon the size of the aquarium and types of corals being kept in the aquarium. If you keep short polyp stony (SPS) corals then these require stronger water circulation therefore with no closed loop devices you will either require stronger devices or more of them.

The other consideration is the physical size of the aquarium. The bigger the aquarium the more water there is and therefore more water to move around.  As with the above example in relation to SPS corals you can therefore either purchase more devices or purchase more powerful ones.

With more than one loop in the aquarium you can provide more outlets to where it is required most. For example if you have a 4*2*2 aquarium which is stocked with SPS corals then you could use stream like devices which do create excellent water circulation however these would be visible within the aquarium or you could create some loops.

In the above example what you could do with a closed loop system is install two loops. Both of these loops would have their dedicated inlet as well as a dedicated pump however you could feasibly have up to six outlets.  Once the pipe work is plumbed back from the pump to the aquarium these could be located in numerous areas of the aquarium. You could have two outlets at the corners in the front bottom of the aquarium pushing water up the rock face, another two could be in the rear upper corner and another couple could be hidden in the rock face. All the pipe work could be hidden from view either within/behind the rockwork or under the sand. All that would be visible would be the outlets and these would become covered in coralline very quickly.

The water flow created by a properly designed closed loop system can be fantastic however there is some planning to do.

The first thing you need to consider is the physical power of the pump. The pumps are rated at zero head height with only one outlet. If you only plan on using this outlet then this will be the output you can expect from the pump. There is no head height restrictions in a closed loop system but I will go over that shortly.

The second thing to plan for is the amount of outlets per loop. It is recommended that you do not go above three outlets per loop as the reduction in flow may be too much. Pumps are rated in accordance with the size of the outlet coming out of the pump and with a pump there is only one outlet. If you put three outlets onto a closed loop then effectively the output from the pump per outlet will reduce. Normally in a loop this reduction is staged with the last outlet having the weakest route – I will cover why this is shortly.

The location of outlets is an important thing to plan for. You don’t want to install your rocks and then plumb around them. It is much easier to attempt to design where you would like the outlets to be. Of course when you aquascape the aquarium this design may have to change a little however it should not need to change that much.

The physical plumbing is also an area which requires consideration. With a closed loop system you will have one pipe for the inlet and another for the outlet. With this plumbing running down to where the pump is located there may be a fair few pipe, especially if you install more than one loop! The run of these pipes will need to be roughly planned for and it is wise to ensure that they are located in an area where they are accessible. If a leak was to occur then you want to be able to get to the pipe work to rectify the issue.

Plumbing is an important aspect to this as there are many ways to ‘plumb in’ a loop. The connections to the pump are fairly straight forward. Either the pipe will attach directly to the inlet/outlet area of the pump or if not you simply attach some flexible tubing to the inlet/outlet, heat up the other end and stretch it over the pipe using bushes if required. It is the inlet and outlet which is important. There are effectively two ways in which the inlet and outlet can be integrated with the aquarium. The first is that the pipe work goes up and over the aquarium edge. Effectively pipe work is run up the exterior of the aquarium and then using bends it is taken over the edge and into the aquarium. On the inlet it is best to implement some type of protective cover to prevent livestock etc being drawn into the pump. The outlet is simply taken over into the aquarium and the outlets plumbed in.

The other way to achieve this is to physically drill holes in the aquarium. One of these would be for the inlet (again covered with a protective covering). In this hole would be a tank connector which the pipe work would be attached to and connected down to the pump. The outlets could either be just the one hole of one for each required outlet. With one hole you could just use it as a single outlet or you could plumb pipe work internally to more outlets. With more than one drilled hole you can split the pipe externally to the aquarium and deliver one pipe to each hole. With all holes you will need to install a tank connector and then connect the pipe to this.

Plumbing the loop(s) in is quite a simple process. It has been briefly covered above how to attach the pipe work to the pump however one area which I would recommend is locating the pump on some sort of media/device which will absorb vibrations. The pump, due to it having moving components is going to vibrate and due to hard pipes being attached to it may sometimes cause noise. If you locate it on some media then this noise will reduce. I have had numerous closed loops and have not been able to hear the noise of the pump. Due to vibration I personally prefer to attach flexible tubing to the pump and then attach the hard pipe to the flexible tube. This method therefore allows for a certain amount of give.

Take your time when plumbing the aquarium. As the old saying goes ‘measure twice and cut once’. You need to ensure that the pipe work you purchase is of food grade quality. Fortunately most quality online and offline shops now stock various types of plumbing components. You will also need some ‘glue’ for connecting the pipes together – this is not just normal household glue it is special glue which again you can get from your local fish shop or reputable do it yourself store.

When you cut the pipe always ensure that the ends have a straight cut. Once the cut is made ensure that any loose areas are moved and/or cleaned and then de-burr the end. You will require connectors to attach the pipes together. Considerations into these are given later. I would recommend not rushing this point and always dry test each pipe/connector. Once you are happy with the connection glue them together. Once the glue is set the only way you are going to be able to get them apart again is by cutting them!

Once everything is in place the next step is to get water into the pipes and all the air removed. If you have drilled holes in the aquarium for the inlet/outlet(s)s then water will already be in the pipe and as soon as the pump is activated any remaining air should be pushed out. To check if there is any remaining in the pump simply rock the pump gently to remove any trapped air bubbles.

If the loops are configured in an up and over fashion then this is slightly trickier to accomplish as the water has not ability of getting up and over the aquarium edge. There are a few options available to accomplish this task though.

The first one is by simply sticking some air line up the inlet pipe so it is as high as it will go and then sucking the air out until you effectively get a mouthful of water. When the pump is turned on any remaining air should be blown out of the outlet. If you choose this option then I would recommend putting a gang valve onto the air line so that you can have a break.

The second one is by drilling a hole in the very top area of the pipe where it goes over the aquarium edge. Into this hole insert some tubing and seal it in place using sealant. It is imperative that a very good seal is made as you do not want any air to get into the tube. Install a gang valve onto the airline and then suck out the air. Once you get a mouthful of water close the gang valve. When the pump is turned on the water will flow however this will create pressure on the gang valve therefore I would recommend that you bend this over into the aquarium and open the gang valve. As the pump is running a small amount of water will flow out of the airline tube into the aquarium.

That’s how closed loop plumbing effectively works however what are the benefits and are there any other considerations?

Before the considerations let’s have a brief look at the benefits of closed loop circulation.

The main benefit is the actual water movement which is created in the aquarium. Due to the large outlets which can be used and the powerful pumps which can be implemented the flow is very powerful however it is also very wide and soft. This is much more beneficial for corals as they require a lot of water movement but they do not want/like water movement which is forceful, in actual fact it can damage them sometimes even tearing the coral away from its skeleton.

Another benefit is that a very un-natural looking device is removed from the aquarium. Power heads etc are very good devices at moving water around however they are, in my opinion, quite intrusive. With a closed loop system the physical device is removed from the aquarium, out of view with only the outlets being visible.

With the pumps being external to the aquarium a heat source is removed from the aquarium. Whilst this heat source may be valuable during the colder months it is certainly an issue during the warmer months. With the heat creating source being physically removed it can, at times be easier to provide stability in relation to temperature.

A very valuable benefit of a closed loop system is that there are no head height restrictions. The rating of the pump is what you should get – even if the pump is three feet lower than the display aquarium. Head height is effectively due to gravity where the water when rising up a tube has to fight against this natural force. The pump can only pump the water so high and then simply runs out of power. If a pump has a four foot head height then at four foot above the pump the water flow will stop, at two foot above the pump the flow will be halved etc. With a closed loop aquarium head height does not exist. The reason for this is that the water does not have to fight against gravity as no air is allowed into the pipe work. The inlet pipe is continuously full of water as is the outlet therefore with no gravity to fight against you get full use of the power of the pump!

The above is the main benefits now let’s move onto some considerations.

The first consideration is that of water flow and friction. Water will always find the easiest route and follow it which is one of the reasons you need to plan your plumbing. If you implement a tee piece for example the water in the pipe will travel down the easiest route and therefore water flow down the secondary path may be severely impacted. Friction is also the same – although the inside of the pipe feels smooth to the touch it will create friction when in contact with the pipe. When in a straight line this friction is not a problem however bends are another kettle of fish altogether. If you need to go around a bend it is easy to install a 90 degree bend however this is quite a bend for the water to go around and the flow will be severely impacted as well as creating back pressure within the pipe which over time may damage the pump itself. If you need to go around a corner then it is better to use two 45 degree bends instead of a single 90 degree bend. Even better is to use rigid pipe which  is slightly flexible which will allow you to create a gentle curve around corners.

When the plumbing is complete and all the outlets are in place it is highly recommended that you perform a dry run. This is probably not the best name for it as water is involved but what I mean is that you fill the aquarium with household water and then test the loops. If you locate a leak then you can lower/drain the water and rectify the problem. If you fill the aquarium with reverse osmosis water, add salt, test and identify a problem then this is a waste of reverse osmosis water and salt – both of which are expensive.

All devices at some point will require maintenance or may even fail altogether. With a closed loop system the pipes are continuously full of water so if you remove the pump then you may get a wet floor as the water continues to flow through the inlet. I would recommend that ball valves are installed into both the inlet pipe and the outlet pipe. Should you need to remove the pump for whatever reason then you simply need to close the ball valves prior to removal. Once the pump is reinstalled the valves can be re-opened plus you won’t need to re-prime the loop!

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Coralline Algae Is Not Supposed To Be White

October 19, 2008

Coralline algae in the marine aquarium in my opinion makes the overall appearance much more attractive and natural.

There are some people who dislike coralline algae and each to their own. I have a personal hatred to having any on the front glass and as soon as I spot any out comes the blade to scrape it off!

Coralline algae comes in a vast array of shapes and various shades of pink/purple as well as other colours – there is one colour that it is not supposed to be however and that is white.

Coralline algae when white basically means that it is either dying or unfortunately is actually dead. If the entire area is white then it is dead, however if either the outer or inner areas are white and the rest still has colour then it is dying.

The white colour is basically the underlying carbonate structure of the algae – very similar to a coral which has expelled its zooxanthellae.

So how can this happen?

Quite a number of things really. It could a be a shift in balance of an important element – for example a drop in Kh in the aquarium. It could be due to the light bulbs being changed above the aquarium and the lights are now brighter. It could be the introduction of new lights. It could be a reduction in water flow. It could be not enough actinic light – the list goes on and on.

There will always be some area(s) in the aquarium where an area of coralline algae goes white. This cannot be prevented as things change inside the aquarium. If coralline was once thriving in an area of high water flow and the water flow is changed then the coralline algae may no longer thrive. I would not worry too much about the occasional area of dying coralline algae but if more than ‘a bit’ starts to turn white then this could be cause for concern.

Some aquarists worry when they see small white spots appearing on the coralline algae. In these cases the area could do with some closer inspection as this might not actually be decline it could actually be worms living on/in the algae.

Rather than go into how to prevent coralline algae from turning white I think it may be beneficial to look at how to actually increase coralline algae growth in the aquarium. If you understand what you need to do to encourage growth then you will hopefully see what is missing if some areas start to go white.

So how do you promote coralline algae growth?

First of all coralline algae does not like bright white light but really like actinic lighting. The first thing you want to consider is increasing the amount of hours that your actinic lights are on for. This is very simple to do by simply changing your timers so that the actinics come on one hour or so earlier and turn off later. Another thing you may want to consider and this does depend upon what else you have in your aquarium is increase the amount of actinic light and reduce the amount of white light.

The second thing is that you want to maintain your calcium at around the 400 mark. Coralline algae is a calcerous algae and therefore needs calcium to be able to grow and expand. As the coralline algae is growing it will deplete the calcium content in the water and you will need to add calcium additives or some other type of supplementary measure to keep calcium at this level.

Magnesium is the next consideration. This level should be maintained at around the 1300 mark. Again additives, supplements etc can be added to the aquarium to maintain this level.

Another element and in my opinion the most important one – strong water movement. Coralline algae does appear to grow better in areas of high flow. Have you noticed in other people aquariums that it appears to grow on powerheads, pumps, overflows etc. Water flow – important for corals, live rock etc but also important for good coralline algae growth.

The final aspect and a word that is said in every aspect of this hobby – patience. You will need to be patient as the coralline algae will not grow and colour up overnight. It will grow slowly at first and probably be so small for a while that you will not even be able to see it. Then after a while it will start to spread covering rockwork, pipes, glass etc and in the end, like me you will be scraping it off the front glass as soon as it appears!

There is another area that needs to be covered and that is the actual introduction of the coralline algae itself. Strangely enough it cannot grow if it is not already anywhere in the aquarium. A good piece of premium live rock will suffice as a seed. What I do when I am attempting to make the coralline spread is remove a piece of live rock from the aquarium and scrape it with a scalpel allowing the scraped coralline to fall back into the aquarium. Where it eventually lands it will hopefully attach and grow. Another method that some people do is not use live rock but use what is called ‘live rock grunge’. GARF manufacture and sell this and from what I have heard people have had amazing results. This method is particularly useful if you do not use live rock in your aquarium and have for example home-made rock or another type of inert rock.

The majority of aquarists aspire to having coralline algae which is a really deep purple in colour. It needs to be noted that you cannot pre-empt the colour that the coralline algae will be. You could purchase a piece of premium live rock which is covered in beautiful coloured coralline and over time it turns into a lighter shade. On the other hand you could purchase live rock covered in a light shade and it turns into a deep colour. The colour depends upon the actual parameters in your aquarium, the water flow, the lighting etc. Every aquarium is unique and that is one of the great things about this hobby.

It also needs to be noted that coralline algae is not always a purple/red colour. It comes in a lot of colours – green, yellow etc however a purple colour is normally the dominant one. One colour which you don’t get however is white – well not that I have ever seen anyway!

There are some products on the market nowadays which are designed to accelerate coralline algae growth. One that I have heard of is one called Purple Up Coralline Accelerator – I have never personally used this or any type of these products as I prefer to do it ‘naturally’ and therefore am unable to comment on their effectiveness even though I have heard that they are quite good.

So if the coralline algae in your aquarium starts to go white then basically ensure that all of the above is correct and correct the one(s) which is off the mark.

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Re-iterating The Importance Of Aquarium Water Movement

October 11, 2008

Seawater that is not moving or sluggish could be close to ‘dead’. In that condition it is not going to carry out the important functions that are necessary.

I remember once reading in a marine hobby book that the aquarist needn’t worry too much about fish and seawater movement, the fish swimming about would create enough movement. Er, sorry, but wrong! Admittedly the book was read many, many years ago and the author would be correct in one respect – as the fish swam along the seawater would move past them. This was written in the days well before corals had made an appearance, but nevertheless we now know better, a fish only aquarium would not be healthy without sufficient seawater movement.

So why is seawater movement so important? The movement supports important functions without which there would be problems.

The seawater needs to move fairly vigorously, not a maelstrom but significant. The movement should not be linear but random and chaotic.

In a fish only system the guideline is around 10 times the net gallonage of the display aquarium. Any gallonage in a sump is ignored. The first thing achieved is that oxygen in the seawater is plentiful. Oxygen is taken in at air/water interfaces, and the biggest one of these is the seawater surface in the display aquarium. Seawater is constantly moving to the surface and away again hopefully saturated with oxygen, which is then carried to all parts of the aquarium system including the sump if used. It can be seen how important sufficient oxygen intake is when it is considered that seawater in a marine aquarium with a high oxygen content is often between 6 and 8 ppm (parts per million). Not exactly a high ratio! In a heavily stocked fish only aquarium the demand for oxygen by the fish is high. Obviously a drop in the oxygen supply would cause fairly rapid symptoms such as fish close to the seawater surface where the oxygen content would be higher. The second advantage to fish is that the seawater movement prevents an ‘envelope’ of static seawater from developing around the fish, which, as I understand it, could interfere with the fish’s osmotic requirements. The movement, on a much more secondary level, makes food move about attracting the fish and inviting them to chase it down.

In a soft coral reef aquarium, fish or no fish, the guideline for seawater movement is the same as in the fish only system which is about 10 times the gallonage of the display aquarium per hour. The seawater is oxygenated in the same way, and the movement brings this oxygen to all parts of the system and around the corals. Branched soft corals can be seen responding to the movement as a field of corn does to wind, and the corals are likely to extend their polyps further than in a system with poor circulation. Some corals would not exhibit their polyps at all. The seawater movement helps the corals clear mucus and debris from their surfaces and also brings food within reach.

Generally SPS (soft coral stony) hard corals require more movement than the soft variety. The guideline is around 20 times the net gallonage of the display aquarium. This seawater movement gives the same advantages to the hard corals as it does to the soft types – it causes better polyp extension, clears the surface of debris and mucus, and brings food. The reason more vigorous movement is required is because of the area the corals inhabit on the reef.

When an aquarist is considering purchasing a coral, consideration should be given to the area on the wild reef the coral would normally inhabit. This will permit better placing of the coral on the captive reef in relation to light and seawater movement. It is quite possible for an aquarist with a hard coral reef system where seawater movement is around 20+ times per hour to keep soft corals (subject to compatibility) – the guidelines are not that rigorous. The seawater movement lower down is often more subdued and suitable for soft corals.

When all is considered, there aren’t that many demands that have to be met for a healthy marine aquarium. Top of the list is seawater quality. This includes oxygen content which means sufficient and appropriate seawater movement is required.

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Filed Under Water Movement · 1 Comment  

Why Is Water Movement So Important In A Home Aquarium

September 24, 2008

Let’s take a quick look at the ocean – it is a vast area which is exceptionally dynamic. The animals which live in the ocean, some of which make it to our aquariums are used to the action of the water movement.

The secret of a successful marine aquarium other than research and patience is optimum water quality, adequate lighting and water movement.

Water movement is not something which is appreciated by marine aquarists but is normally something which is provided as it is believed that it needs to be provided. To appreciate the important of water movement it is important to understand its role in nature, understand the requirements of the animals and then finally work out the best way to provide the required water movement.

Water movement’s role in nature is for many things. It allows for gas exchange, the provision of dissolved oxygen, the provision of food to animals, the removal of waste, the exchange of nutrients between filtration methods (In the wild this could be between the reef itself and grass beds/mangroves etc).

Water movement within the home aquarium has a simple term which is simply ‘turnover’ which is also classified as the amount of water which is moved around the aquarium per hour. There is a standard minimum turnover for a reef aquarium which is 10 times per hour. Therefore if you have an aquarium which is 100 gallons then you will need to ‘turnover’ the aquarium water 1000gph.

It is not as simple as purchasing the correct amount of water pumps, powerheads, wavemakers to facilitate the correct amount of turnover. There will be some fine tuning required in order to provide the correct types of currents to the animals in the aquarium. This is especially true when corals are being kept as their water movement requirements are higher than that of fish. Corals unlike fish do not have the ability to be able to walk around the aquarium in search of the ultimate spot. Some anemones do have this ability and move around the aquarium looking for the perfect location. Unfortunately quite often this is round the rear of the tank out of sight!

I shall have to get a little bit scientific here in order to explain why corals require strong water currents. Hopefully it will not get confusing. When water flows around a coral its viscosity increases due to friction. At the water/coral interface the water is at its highest viscosity – basically the water becomes really thick and due to this a stagnant area of water is evident around the coral. When this happens the coral literally poisons itself due to the inability for diffusion to occur. Obviously this is not something that we want to happen and the correct amount and type of water movement needs to be implemented. We cannot just point an outlet from a powerhead directly at a coral as this will not be appreciated and could again kill the coral.

Whilst fish do not have the same requirement for strong water movement as corals do there are a lot of fish who respond better when kept in an aquarium with strong water currents. Feeding time is more natural and the fish continuously move themselves around to be in the correct flow pattern where both essential oxygen and food is provided.

Another area to consider is the filtration itself. If live rock is used then enough water movement needs to be provided to allow the water to be able to move over, around and into the rockwork so that the bacteria can do its job. If not enough water movement is provided there will be areas in the aquarium where the water is not moving and stagnant. These areas effectively become bad and are not being processed by the filtration. Live rock can only process the water which passes over it therefore if the water is not moved to the filtration area then quite simply it will not get processed and before long the water quality will begin to suffer. From here the slippery slope begins.

One area which is often forgotten about is the air interface – the surface of the water. If flow water movement is provided then the low oxygen areas in the water will stay near the bottom of the aquarium and the oxygen rich areas near the top will stay near the top. For the air/water exchange to work effectively the surface of the water needs to be broken. This can be achieved in many ways – it can be achieved using a spray bar, a small powerhead pointing up to the surface of the water or can with enough water movement in the aquarium be created all on it’s own.

What we need to achieve is a lot of water movement in the aquarium using what is called a wide flow. The output from a powerhead is a thin flow and whilst powerful is damaging. The flow itself does not want to be laminar in pattern i.e. all in one direction instead it needs to be chaotic/turbulent.

Looking at the corals in the wild we can see that they sway in all directions as the water currents move them around. If you have ever been scuba diving or even snorkelling on/over a reef then you will appreciate how water movement in nature works.

Another type of flow which is very popular is what is called surge flow where the water flow in a back and forward type of action. There are various devices available which assist in the creation of this type of flow and also various do it yourself plans available however personally I believe that even this type of flow needs to be broken up so that is becomes turbulent.

I am a firm believer in trying to emulate nature as much as possible in the home aquarium and water movement is no exception. Quite often in the wild the water currents reduce due to the lack of wind at the waters surface. Again this is relatively easy to achieve with a light sensor which either reduces the speed of the pump or turns it off altogether.

The aquascaping in the aquarium will also have an impact on the flow in the aquarium. When the water flow hits or passes over the rocks then friction will occur and this will effectively reduce the amount of flow in the aquarium. The same can be said for corals especially hard corals as they grow larger. As they grow the flow in the aquarium will change and will need to be periodically reviewed. Due to the rocks and corals in the aquarium there will be areas of the aquarium where the water flow is significantly different. This is not too much of a problem as long as corals are placed in locations which are suitable for their requirements – both water movement and lighting. It is imperative however to ensure that there are no areas of stagnant water as this will create problems further down the road.

When planning the water movement in the aquarium there are normally two factors which are taken into consideration. The first one is the requirements of the animals in the aquarium and the second one is cost.

Powerheads are normally the aquarists first choice as they are cheap to purchase and can create good flow within the aquarium with careful positioning. As already stated we need to be careful to ensure that the flow is not pointed directly at a coral as damage can occur.

Wider pumps are available which have a much wider outlet and instead of an impellor have a propeller type device and this creates a strong yet soft flow if that makes sense which therefore means that flow can be provided which is much more beneficial to the corals in the aquarium. Care still needs to be taken with placement so that no damage is caused to the corals however the flow created is much more natural.

There are various other methods which can be utilised. Wavemaker devices can be implemented to create random flow. These can be automated devices which switch pumps on and off to create a random flow. Again care does need to be taken with these are powerheads/pumps are not created to be turned on and off all the time and damage can occur to the powerheads/pumps. Other wavemaker devices are also obtainable which are similar in design to those of wavemaker devices in swimming pools.

Another option which is my personal favourite is the implementation of what is called closed loop. This is where the pumps are located outside of the aquarium and flow is directed into the relevant areas of the aquarium using pipework.

It is my opinion that water movement is one of the six important factors of a successful home aquarium.

These are:

Planning, patience, research, water quality, lighting and water movement.

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Filed Under General · 3 Comments  

Have A Soft Flow For Better Polyp Extension

August 31, 2008

Seawater movement in the aquarium is a known requirement. This movement is needed by all marine aquarium creatures to a greater or lesser extent.

The aquarist who keeps a fish only system may believe that seawater movement is not so important and that belief is correct. However, fish need reasonable movement to prevent an area of ‘dead’ seawater developing around their body. It is also much more natural to have healthy movement as this is after all what occurs in their natural habitat, the wild reef. Fish also have a strong demand for oxygen and seawater movement maximizes good gas exchange.

Corals have a greater demand for seawater movement generally. This demand does vary between types, for example soft corals, again generally speaking, need less flow than hard corals, particularly the SPS (small polyp stony) types. As a general guideline to seawater movement, in the aquarium a soft coral display requires around 10 times the net gallonage to be moved per hour, and hard corals around 20 times or more. This movement is within the display aquarium, and does not apply to seawater moving through a sump.

The normal way of generating this movement is to employ power heads. More than one is usual, so that the outputs clash and chaotic and random movement is achieved. The output of the normal power head exits from a nozzle of, say, ½” (circa 12mm) in diameter. As this nozzle is narrow and the output is high, the seawater forms a powerful and narrow stream. This can be damaging to corals should it have a direct impact and care is needed in the coral’s placement. Even then corals in a good environment grow and may enter the high speed stream zone.

There is a relatively new type of power head now available which serves the same purpose as the type mentioned already. There is a very significant difference however, and this is that the nozzle is much wider, measuring around say 2½” to 3″ (circa 63mm to 75mm). Seawater leaving exits in a much gentler manner, which is not in a narrow stream but in a broader front. As the seawater stream is not so damaging the amount of seawater that is moved can be significantly increased over the older types of device, so the total amount of seawater that needs to be moved per hour is more easily achieved. The movement is more natural as well, as the stream forms, as said, a wider front. In the same way that the older power heads can be used in opposition, so can the wide output types. In fact, if two or more are used in opposition on timers then a wave system is not that difficult to generate.

The result of all this is generally happier corals. Provided the currents are not so strong that soft corals are being overcome by the surge and even hard corals are hard put to expand properly, the aquarist should see the corals are expanding and extending their polyps noticeably more.

The only time when the wide outlet power heads could need their output reducing is at feeding time to enable the fish to feed at leisure. Control units for the power heads, if used, normally have this ‘pause’ facility built in. Some aquarists also reduce the output of the power heads at night.

Anything that makes the aquarium environment a more natural one isn’t a bad thing, and the use of wide outlet power heads is a step in this direction.

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