Re-iterating The Importance Of Aquarium Water Movement

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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Tags: aquarium, Aquarium Water, home-aquarium, marine-aquarium, Water Movement, Water Quality

Why Is Water Movement So Important In A Home Aquarium

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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Tags: Aquarium Filtration, Aquarium Lighting, Aquarium Maintenance, Care, Equipment, Water Movement

Have A Soft Flow For Better Polyp Extension

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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Tags: aquarium-pump, Corals, Equipment, power head, reef-aquarium, Water Movement

Aquarium Equipment - The Peristaltic Pump

Aquarists use different types of equipment to assist in the running of their aquariums. These can be very important ‘must haves’ such as a protein skimmer and circulation pumps, or labour saving devices such as an automated evaporation top-up device or calcium reactor.

One piece of labour saving equipment is the peristaltic pump. This device originated in the medical profession where medications needed to be applied to patients in precise but low amounts over time. The device has been found to be useful in the marine aquarium hobby and there are models available manufactured for this purpose.

The units vary in size, some perhaps 1″ (circa 25mm) in thickness by perhaps 4″ (circa 1.2mm) square. The ones destined for use with an aquarium are usually constructed of plastic, often with a clear panel on one side. The clear panel enables the owner to see the flexible tube inside.

The unit is powered by a small electric motor which to all intents and purposes is silent. This drives a shaft which revolves very slowly. As it revolves it usually drives three arms and on the end of each arm is a roller. A flexible tube about ¼” (circa 7mm) in diameter enters at one side of the unit and exits from the same side but the other corner. The flexible tube goes in a circle within the unit. When running, the rollers which are moving slowly in a circle compress the flexible tube and force any liquid present forwards in the same direction.

The pumps can be obtained in various outputs and with either static or variable speed. The static speed ones are of course less expensive. They run very cheaply on mains electricity and can be used with electric timers. Fitting them is simplicity itself, most being fitted upright in a convenient location out of sight but accessible and away from the danger of getting wet from seawater. The intake end of the tube should be fitted with a filter which is easily constructed - a small piece of fine filtration sponge with a narrow hole is the often used method. The outlet end of the tube could need holding down with a sucker or small weight as it might tend to float to a horizontal position.

The aquarist can make use of the pumps in several ways. Sometimes it is difficult to adjust the flow rate of an anti-nitrate filter (a de-nitrator) and a pump could be selected to move seawater through the filter, thus solving the problem. Or, provided the aquarist knows the demand of the aquarium, supplements could be applied for the appropriate period per day to meet the need. A watch would need to be kept that mixtures remained viable, that is did not de-mix over time, and also that clogging did not occur.

One area that the pump cannot be used for is timed feeding. This is a great shame as it is ideally suited and could successfully dose an aquarium accurately according to the demand of the livestock. So why can’t it be used? It is simply because the food goes off. The pump needs a small reservoir so that timed feeding can occur. During this time the liquefied food morsels could fall to the bottom of the reservoir, though the problem could be avoided by a simple stirring system. As said though, when waiting to be used the food deteriorates. Experiments have been made with refrigeration devices, all by aquarists but as far as I know a successful solution has not been found. If feeding could be done with the aid of the pump then more natural feeding over the daylight hours could be accomplished, rather than the one or two heavier meals a day that usually occurs.

There is very little to go wrong with a peristaltic pump. The item to watch is the flexible tube inside the pump in the region where it is compressed. Over time it starts to fail and needs replacement. The tube is not expensive and so a length can be kept as spare. Some manufacturers supply this spare tubing with a new pump.

So if the aquarist is having difficulty in supplying a correct flow rate or wants to apply precise amounts of liquid to the aquarium a peristaltic pump could be considered.

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Tags: Aquarium Maintenance, Aquarium Water, aquarium-pump, Care, Equipment, Water Movement

One Return Pump Or Two?

What is a return pump? These pumps are used for returning seawater from a sump to the display aquarium. They are used in fish only aquariums and reef aquariums, provided the system includes a sump of course.

Equipment nowadays is generally very reliable and many aquarists don’t back-up anything. Fair enough, but any item of equipment however good can fail.

General good practice suggests that important equipment in the system should be backed up where possible. This is clearly not done in the case of lighting and display aquarium circulation pumps. Important as these are it is impractical and unnecessary to have a back up. In the case of circulation pumps, the aquarist could have a spare in the cupboard, but the loss of some circulation for a short period is not a problem so this is unnecessary.

One of the most important areas in an aquarium is the bio-filtration. Some would argue that it is the most important area as without it the whole system will fail, that is the livestock will suffer or be lost. So if canister filtration is the method in use, two canister filters are a good idea in case on fails.

Anyway, to get back on track. The return pump. Seawater gets to the sump by means of gravity and an overflow in the display aquarium. It flows through the sump and is pumped up again. Looking at the pump and its job, is it important enough to require a backup and if so is it practical?

One of the benefits of a sump is that it can house items such as a protein skimmer, heaters and possibly a deep sand bed (DSB). This being the case it would be detrimental for seawater not to be exposed to the protein skimmer for a long period of time. Similarly, the seawater needs to be maintained at the proper temperature. So the flow through the sump needs to be reliable. So a back-up is desirable.

One of the items that the aquarist should check when at the aquarium is flow, and a lack of flow from the display aquarium to the sump is very noticeable. Seawater loses heat slowly (the loss rate being subject to circumstances) so heat loss is not of great concern, the loss of flow should be noticed before any problem arises. The lack of flow will not be noticeable on the protein skimmer as it will continue to function though will fail to remove organics as they are not going through the bubble chamber. Any DSB will not be affected as seawater is present, though benefits such as nitrate reduction could temporarily be interrupted.

From a practical point of view, a back-up return pump is best considered in the sump design stage. Many sumps have a sectioned off area that is capable of housing one pump only. If two are to be used, the sectioned off area will need to be that much larger, unless the pumps can be fitted one above the other.

If two pumps are to be used, should they be of equal pumping capacity? The guideline for the flow rate through the sump is around three times the net gallonage of the whole system, that is display aquarium and sump, per hour. So two pumps together need to provide this, each pump having one half of the pumping capacity of a lone pump, that is, each pump needs to be able to deliver around one half of the required flow rate. Both pumps are very unlikely to fail at the same time, and the failure of one pump means that the flow rate through the sump will be half of that intended. This will be enough to maintain heat distribution, and will continue to present organics to the protein skimmer. The DSB will also continue to function.

If the aquarist does not check flow rates when feeding or admiring the display aquarium, or uses an automatic feeder and doesn’t check the aquarium particularly regularly, then having two return pumps is a good idea. If checks are regularly made and the aquarist is confident that a changed flow rate, or lack of one, will be fairly quickly noticed, then two return pumps are not really necessary. Consideration needs to be given however to how quickly a replacement pump can be obtained should this be required.

The individual cost of pumps where two are used will be a little lower because of the lower pumping capacity, so the extra cost over one pump is not great. It is a good idea overall to protect important system functions where practical, and the use of two return pumps is good and follows this principle.

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Tags: aquarium, aquarium sump, Aquarium Water, Equipment, Water Movement, water pump

Water Movement In The Display Aquarium

Both the reef aquarium and fish only aquarium have certain demands that are very important. Top of the list is water quality, followed by lighting (for a reef anyway).

Water quality is of course measured, and for both types of aquarium the four basics are the same - ammonia, nitrite, nitrate and pH. With the reef the list is extended, taking into account for example alkalinity, calcium, magnesium etc.

Water quality is more than measurement however. Though a personal thing, I count water movement as part of quality. Water movement brings oxygen and food to corals, and helps removes dirt and mucus from them. It ensures fish have sufficient oxygen, and also makes them feel more ‘at home.‘ It also oxygenates a reef and assists in keeping it clean. The seawater is ‘clean’ and freshened in all parts of the aquarium. With good water movement the very important gas exchange is achieved - water is continually delivered to the surface to re-oxygenate.

Plenty has been written on this subject, and on this website, already about water movement and its creation. The methods are generally straightforward.

However, I suspect that many aquarists, particularly newcomers, look at water movement as circles. There’s the aquarium, and the guideline suggests water movement of, say, 10x the net gallonage per hour. Easy! Get a couple of powerheads which pump that amount of water, or somewhere near, and the job is done.

If suggestions have been understood, the powerheads are placed strategically to create chaotic and random water movement. Still well and good.

It is thinking ‘in circles’ though. Perhaps it would be better to say thinking ‘horizontally.’ No matter how carefully the powerheads have been placed the seawater cannot possibly reach all parts of the aquarium with good movement. All aquariums have quiet areas where corals that prefer calm can dwell.

So the aquarium is equipped with what seems to be sufficient power to move the water. Probably it is.

What about the ‘vertical’? No, I don’t actually mean pump water vertically in the aquarium, I mean deliver water low down from higher up. What about one additional powerhead that is in an accessible position but pumps water through a tube to, say, a spray bar behind the lower reef or even under it. There are different ways of delivery. All the powerhead needs is a sleeve on the intake (sponge or similar) to stop debris and that’s it. Maybe two powerheads would be required. Whatever.

The aquarist can then be more sure that water quality is high everywhere, with the benefits that can bring.

Advanced systems can use carefully designed closed loops, where the water outlets are positioned in strategic places to ensure fully advantageous delivery. The ‘ordinary’ aquarist need not go to these lengths unless really desired. The use of additional water movement devices, one or maybe two, will do a fairly similar job at a very reasonable cost.

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Tags: aquarium, Aquarium Water, reef-tank, saltwater-aquarium, Water Movement, Water Quality

Guard Those Intakes!

Be it a fish only aquarium or a reef aquarium, there are going to be intakes to canister filters, protein skimmers, sumps, power heads and the like. The equipment fitted is important to the quality of the seawater and its movement.

This water quality is to enhance the life of the inmates. There is a danger that the intakes to devices such as the examples given could in fact be a threat to mobile livestock such as fish and shrimps. There is also the danger that other livestock such as corals could be damaged if they grow or are placed too close.

Taking corals first, and really considering the soft variety, many are able to grow to quite a size. If this growth brings the coral anywhere near an intake then the coral tip could be sucked in and damaged.

Fish and shrimps like to find hide holes that are secure. It has been known for them to enter an intake with a view to a secure home, only to become stuck because of the water flow and subsequently die. It has also been known for a small fish to end up in the sump, having journeyed down the feed pipe. Lucky in that case and usually no harm done. Established fish could be searching for a better home, perhaps because another fish has taken over their previous residence. Newly introduced fish have a priority to find a home and safety, searching carefully and investigating anything that looks hopeful to check if it is occupied.

Quite apart from the potential danger to the trapped fish or shrimp, there is the question of the interruption to the water flow. This could be serious in certain cases if not noticed by the aquarist for a while.

The potential problem is easily avoided by always using the intake guards that are provided with powerheads, canister filters, protein skimmers and the like. If there is any other intake, perhaps one incorporated by the aquarist in the design, it is simplicity itself to put a mesh guard over it.

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Tags: Aquarium Maintenance, Care, Equipment, marine-aquarium, Water Movement

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