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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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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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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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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Closed Loop Circulation – How Hard Is It To Install

Creating good water movement in the aquarium is required in order for the [tag-self]aquarium filtration[/tag-self] (if live rock is used) to be both efficient and effective, for the correct oxygenation to occur and for the transport of both food and waste around the aquarium.

A lot of aquarists simply utilise a few (or more) powerheads and strategically place these around the aquarium hoping to create the required water movement. In a lot of cases this works and the water movement created is excellent. Other aquarists also decide to utilise spraybars under or behind the rockwork as well as near to the water surface.

With enough patience mixed with a bit of ingenuity excellent water movement can be achieved.

There is another way though and in my opinion it is a better way.

Closed Loop Circulation.

There is a lot of confusion when it comes to closed loop circulation and to be honest once you understand how it works it really is not that hard to implement.

Closed loop circulation works by water being taken from the aquarium down to an external water pump, this water pump then pushes the water back up to the aquarium where the water circulation is created.

The above is a very high overview as to how closed loop circulation works so I shall try and go into a litle more detail.

The water inlet is submerged in the water. This can either be via overflow pipework which goes up and over the aquarium lip and down to the water pump or it can be via a hole drilled in either the side or base of the aquarium.

This pipework is then attached to the water pump. In a lot of cases it is impossible to directly attach the rigid pipework to the pump so the rigid pipe needs to be attached to flexible tube which is then attached to the pump. Actually I would not recommend attaching rigid pipe to the water pump due to possible vibrations created by the water pump. The rigid pipework can be attached to the flexible pipework by heating up the flexible pipe and then gently stretching it over the flexible pipework.

The outlet of the water pump needs to be attached in the same manner.

The pipework is then returned to the aquarium again either by going up and over the aquarium lip or via drilled holes in the aquarium base.

As with the inlet the outlet needs to be underwater.

The outlet is the interesting part. You can have one outlet or you can have two, three possiblly more. The number of outlets depends upon the power of the pump and how creative you are with your plumbing. For example you could have a single closed loop and from that closed loop have 3 outlets at the bottom front of the aquarium pointing up the reef face (one on the front left hand corner, one in the center front and one in the front right hand corner). All of this from one pump!

Of course you do not need to have just one closed loop, you can have as many or as few as you want or need.

Lets pretend for example you have three separate closed loops. One of these is pushing water up the reef face from the front (closed loop 1(very good for oxygenation)), another is pushing water through the rockwork from the rear (closed loop 2) and the thrid is near to the water surface at the top to create additional water movement (closed loop 3). You would get a huge amount of water movement from those loops. Now imagine what you could do with a bit of creativity. You can get the exact [tag-self]water circulation[/tag-self] that you want and your aquarium needs.

Lets step back a little. Why do both the outlet and inlet need to be under water?

In a closed loop system there is no oxygen whatsoever in the pipework. There is just water. For this reason there is no head loss on the water pump, therefore you will get all the power out of your pump without losing any power at all. The reason for this is that the water does not have to fight against gravity and is being pushed upwards by the water pump. At the same time water coming dowm from the inlet is being pulled along by the water in front of it which in turn is also strangely enough pusing the water along in front of it.

So how do you remove all of the oxygen from the pipework?

It is important to note at this point that it does not matter if the outlet is of drilled hole type or the up and over the lip type. The important part is the inlet.

In a closed loop where the inlet is a drilled hole in the aquarium then this is very easy as the water will flow down through the hole down to the pump. At this point you simply turn the pump on and all the remaining oxygen is pushed out of the loop – job done.

In a closed loop where the inlet goes up and over the aquarium lip you need to be able to lift the water up into the pipe until it overflows down to the pump.

This is actually very easy to do and there are a couple of ways to do this.

The first way is to simply push some airline into the inlet right to the upper bend and then suck all the air out. Once you get a mouth full of salt water then you are done. Cover the airline so that air does not get sucked back in and start the water pump. The water pump will push any remaining air out of the loop.

The second way is to drill a small hole in the top of the pipe (right where it overflows over the top of the lip). In the hole insert a piece of airline and a gang tap. Then simply suck on the pipe until you get (or nearly) a mouth full of saltwater. At this point close the tap and start the pump. As before the water pump will push out any remaining air.

On a closed loop system I would reccomend that you install shut off valves into the pipework onto both sides of the water pump. This way you will be able to close the taps and remove the water pump for maintenance or replacement if the water pump fails for whatever reason.

One thing that must also be noted is that the water pump does not need to be located underneath the aquariun. It can be located to the side or even above the aquarium. The reason I prefer it underneath the aquarium is that it is easier to prime the loop (remove the air). When the pump is above the aquarium you have to suck air out of the tube and this can take a whike – much easier when the pump is under the aquarium.

In my opinion closed loop circulation is fantastic on a [tag-tec]saltwater aquarium[/tag-tec]. You can have as many or as few loops as you want. You can have the outlets in the exact location you want, you can have pipework the width you want (the wider the width the gentler the flow) and you can have more than one outlet per loop.

On another note with the water pump being external to the aquarium a heat source is removed and that has to be good in itself.

So have a think about it. As said powerheads etc can and do work. I have used them with great effect, however I personally feel that you can create much better water circulation in the aquarium via closed loops. For example it would be hard to have power heads at the front of the aquarium pointing up and not look unsightly.

Yet you can with closed loops and a lot more.

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Closed Loop Circulation – What’s That Then

After water quality and then lighting water circulation, in my opinion comes next.

Not just any water circulation though – you can’t just chuck powerheads left right and centre into the aquarium and turn it into a washing machine – you have to create the right water flow.

The water flow which you need to create depends upon the livestock you keep in the aquarium. If you are a fish only aquarist then the water circulation requirements are minimal. Corals, however are more demanding in water circulation for various reasons.

Years ago the only option which was available to saltwater aquarists was the powerhead and to be honest we had to be creative as to the ways we positioned these powerheads to achieve optimum results.

Nowadays as both manufacturers and aquarists have learnt more about the requirements of the animals we keep there are more options available to us.

There is one option which I believe stands out above the crowd though and that is one which is called closed loop.

Closed loop circulation is where the device which creates the waterflow is housed external to the aquarium, quite often beneath the aquarium, however it can be placed anywhere. Rigid or flexible tubing is connected to the device which connected to both the inlet and outlet of the device which both go to the aquarium.

A lot of aquarists who use closed loop circulation opt to drill the aquarium and use bulkhead connectors and taps to connect the external device to the aquarium, however you do not need to do this if you don’t want to – you can go up and over the edge of the aquarium if that is easier for you.

Basically what you are doing is allowing water to be pulled from the aquarium to the external device, we will use a external water pump for this example. This pump then pushes the water along the output back into the aquarium and whilst doing this pulls more water behind it.

Now here is the good thing. In a closed loop circulation system there is no air in the pipes which means that there is no head height plus as the pump is external to the aquarium there is no heat transfer from the pump to the aquarium water.

You can setup as many closed loop as you want however each one will require it’s own dedicated pump. A huge benefit of this is that with clever plumbing you can take water from the aquarium from exactly where you want it to be taken plus you can return it to an area in the tank where you want it to be returned to.

One thing I must point out though is that if you do decide to opt for a closed loop system then I would recommend that you install close off taps to both the inlet and outlet areas of the plumbing. Doing this will allow you to remove the pump it either it requires maintenance or replacement.

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Water Circulation In The Aquarium – Why Is It So Important

The provision of water circulation in the saltwater aquarium is dependant upon what [tag-tec]filtration[/tag-tec] method you are using and ultimately the life you are keeping in the aquarium.

A few methods as to how to create water movement has been detailed in some previous posts, however I realised that I have never actually gone into depth as to why water circulation is so important.

This is something I hope to rectify with this post. [Read more]

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