The Location For A Deep Sand Bed

The deep sand bed (DSB) is a popular filtration addition used by many aquarists. Also, interest is added to the aquarium – the DSB over the course of time should develop its own population of life.

Using live rock for bio-filtration is popular nowadays. Linking the live rock with a DSB gives a really good filtration base and the overall environment of the aquarium should be improved.

The question is, where should the DSB be placed? The first and obvious choice is the display aquarium because the sand will also provide a decorative effect. Is this the best choice though?

The DSB is at least 4″ (circa 10 cm) deep, so at the front viewing plate this depth of sand will show. This may not bother the aquarist, and if it does it is a simple matter to place a decorative strip across the bottom of the front glass. So that isn’t a problem.

One problem often arises because of the construction of the DSB. This is from very fine sand, so fine it can drift easily. It is very important for the health of livestock that the seawater has sufficient movement. These currents could easily blow the fine sand and spoil the sand bed. Much like sand affected by waves on the shore, the sand could pile up in some areas. It could even leave a bare aquarium bottom in others. This is obviously not desirable as the sand may rise above the decorative strip placed to hide it, and worse the DSB will not properly function. The fine sand could also accumulate on rockwork which would spoil the décor.

A DSB in the display aquarium could have another disadvantage. Rockwork is always placed on the aquarium bottom, or raised above it on a plastic support, not on the sand. This avoids instability and avoids sand compression. The DSB is pushed around the rock base and at first could look decorative and natural. It is a potential area for accumulation of detritus as seawater flow may well be reduced low down in the aquarium, particular around some bottom areas of the rockwork. This detritus needs to be removed with minimal disturbance to the sand, a task that is not particularly easy with fine sand present.

Livestock such as fish are usually present in an aquarium, the exception being the coral only reef. Fish are constantly looking for food and the tiny life that should appear in and on the DSB will be subject to predation. This sounds fine as live food is good for fish. However, in such a small area this sand dwelling life may not survive the predation. Some will survive in the live rock, but sand dwelling life is important to the health of the DSB.

So if having a DSB in the display aquarium is not the best course of action, what is? Many, perhaps most aquarists have a sump. This may have equipment in it and be used solely for this and the extra seawater gallonage it provides. If this is the case then a DSB could go in.

The aquarist will still require the sump to house equipment and this can be arranged. Fixing a glass or marine safe plastic plate into the sump to keep sand away from the return pump is straight forward, even with an operating system. If heaters are present they can be positioned above the DSB, and if a protein skimmer is present the intake can be the same.

The guideline for the minimum surface area of a DSB is 2/3rds the base area of the display aquarium – this is not always achievable, so the largest area that is should be used. The sump probably presents the largest area as the whole of the base, excluding the return pump area, is available. It depends on the size of the sump used of course. In the display aquarium the area between the rocks and the aquarium glass is available, and then not often down the back.

There will not be a problem with fine sand blowing about – the guideline for the flow rate through the sump is 3 times the total system gallonage per hour. The DSB can be placed into position more easily and the depth can be uniform. There will not be a problem with unwanted detritus and if anything does accumulate it can be more easily removed.

The life forms that inhabit the DSB will be protected from predation, though there will probably still be predation from other tiny sand living life. The DSB life is more likely to maintain its presence and population.

There is another way that a DSB could be introduced and that is to include an area above the sump to include it. This is done by placing a shallow (5 or 6″ high (circa 12.5 to 15 cm)) glass container above the sump, level with one end but stopping where the pump area in the sump begins. The down feed for the seawater from the aquarium is diverted to the DSB at one end; it then overflows at the other into the sump, being returned to the display aquarium as usual. It doesn’t take a lot of imagination to find alternatives to the same theme. This method keeps the sump area clear for other uses, and doesn’t add much seawater to the system (though adding more gallonage is not a bad thing).

Some aquarists run their display aquariums bare-bottomed, though the bare bottom doesn’t usually last long as various marine growths take over. Others employ a decorative sand bed 1″ to 2″ deep (circa 2.5 to 5 cm), this one made of coarse sand, though this too could be blown by seawater currents. The advantages of having a decorative sand bed are that there aren’t any filtration requirements so changes to the bed don’t matter, and they are easier to clean by stirring if dirt appears.

As said, keeping a DSB is a good move in aquarium husbandry. For practical reasons, it is better housed away from the display aquarium.

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The Fluidized Bio-Filter

Bio-filters in marine aquariums are of enormous importance. Without the nitrogen cycle that is provided by Nature all aquarists would soon be in trouble. All those bacteria working away so industriously are doing us all a favour.

Bio-filtration, or the life support system as some aquarists call it, comes in several guises. The current best is live rock, whether that is aqua cultured or from the ocean. The rock from the ocean offers the possibility of a greater diversity of life in addition to the desired bacteria, but this includes of course unwanted life, such as certain crabs and shrimps, not to mention aiptasia anemones (now aren’t they just every aquarist’s favourites!).

Then there is the canister filter, a device that has been in use for many, many years. They are much improved nowadays with much easier access, meaning that most have got rid of those fiddly little clips that used to be used to keep the lid on. Most come with removable chambers thus making the insertion of media for mechanical, bio or chemical filtration easy. The canister is really well proven and highly reliable. Though not often thought of this way, they really operate a ‘closed loop’ when connected.

There is a further piece of equipment that isflui designed for bio-filtration, but it is not so well known. This is the fluidized bio-filter. Basically the device is a tube usually constructed of acrylic, with an inlet at the bottom and an outlet at the top. Inside is a quantity of sand – not just any sand but a type that resists wear in the tumble action it has to endure. A pump or powerhead is connected to the bottom inlet and the outlet at the top is fed back to the aquarium, usually at the opposite end. Sometimes the device is supplied with an inlet filter to help keep the sand clean, but if not it is easy enough to put a foam filter on the pump or powerhead.

As the seawater is pumped through the sand, the sand is ‘fluidized’. This means that the flow of seawater pushes the sand upwards with enough force to keep it loose, but not enough force to make it hurl about the tube. The result is that each grain of sand presents all of its area for colonization by bacteria. Such is the area that a fairly small unit can deal with a fairly large aquarium. Of course this also depends on the bio-load – a fish only system usually presents a larger load than a reef system.

The downside of this type of bio-filtration is that the nitrogen cycle will operate very efficiently, the bacteria converting ammonia to nitrite, then nitrite to nitrate, but it stops there. So nitrate will slowly build up in the seawater degrading its quality. This also applies to a canister filter.

The fluidized bio-filter is a perfectly viable alternative when a system is being considered. The units are usually ‘hang-on’ and easily fitted. The sand in the tube tends to degrade over a long period and the manufacturer often puts in a small bag for replacement purposes. The manufacturer will also advise the flow rate that is required to fluidize the sand correctly.

It is important that the aquarist maintains good general seawater circulation in the display aquarium as the bacteria that inhabit this type of device depend on the seawater’s oxygen content, in the same way as a canister filter and live rock. Also, in addition to the other benefits, routine seawater changes are required to control any nitrate build up.

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You Need To Have Enough Filtration In Your Aquarium

A successful marine aquarium is a wonderful sight. It doesn’t matter whether it is a fish only, coral only, or fish and coral system, there are certain items that need to be up to the job.

The first essential requirement is seawater quality, closely followed – at least in a coral only or coral and fish aquarium – by lighting. It is the need for seawater quality that makes filtration so important.

There are basically two types of aquarium filtration, excluding protein skimming which is often counted as such. The first is mechanical/chemical filtration and the second biological.

Mechanical filtration is where media removes sediment from the seawater by trapping it in suitable media. This is often done by using a canister filter which needs to be cleaned regularly and the media changed if it is showing signs of wear or failure. Mechanical filtration is not an absolute requirement and many aquarists do not use it. It is usually only necessary when there is a fair amount of sediment floating around in the seawater. Before employing a mechanical filter, it is best for the aquarist to ascertain why there is sediment and try to correct the problem.

Chemical filtration is also often done by using a canister filter and can be in conjunction with a mechanical stage – if so the mechanical stage normally comes first. Chemical filtration covers activated carbon, phosphate removing media etc. Again it is not mandatory to use this type of filtration, though some aquarists use activated carbon to supplement the protein skimmer and others run an anti-phosphate media continuously (phosphate is a nuisance algae nutrient and is mainly introduced with food).

By far the most important filtration is biological, and this applies to any type of system. The filtration carries out the ‘Nitrogen Cycle’, which is something all aquarists should clearly understand. Livestock introduce a toxin into the seawater, namely ammonia. This toxin is deadly to life forms in low concentrations but fortunately Nature has the solution. The biological media provides a home for bacteria in their millions, and the first group of bacteria convert the toxic ammonia into nitrite. Unfortunately nitrite is also a toxin and very nearly as bad as ammonia. However, a second group of bacteria convert the nitrite into nitrate, which, though problematical in a high enough concentration, is not generally harmful. If the Nitrogen Cycle is able to run the full course the nitrate is converted to gas which escapes the seawater.

There are one or two points that need to be remembered about the bacteria that provide this essential service. The first is that the bacteria that convert ammonia and nitrite are oxygen hungry, and to ensure their proper function it is necessary to provide seawater rich in oxygen by having adequate seawater circulation and air/water interfaces.

The bacteria that are able to convert nitrate to gas are not the same. They would use oxygen if it was available, but if it is not they take the required oxygen from the nitrate, thus breaking it down. Therefore the bacteria need to be in a very low or no oxygen environment to ensure that the required function is performed.

If for example a canister filter is being used for biological filtration the media is constantly exposed to oxygen. Therefore the breakdown of ammonia and nitrite will occur but nitrate conversion will not. Nitrate will remain in the seawater and will increase unless other adequate measures are taken.

If the biological filtration is by good quality live rock, then the full Nitrogen Cycle, that is ammonia-nitrite-nitrate-gas, should occur. This is because the oxygen loving bacteria accumulate near to the surfaces of the rock, and the bacterial nitrate converters are deep inside where oxygen is depleted.

Having considered all of this, it is clear that there needs to be adequate filtration material to accomplish the biological task. For example, a fish only system can employ live rock. Fish are producers of ammonia, much more so than corals, and an adequate amount of good quality live rock is needed to process the toxins. The live rock amount would need to be increased if the fish numbers were high as obviously there would be more toxins produced. As a general guideline 1½lbs of good live rock is considered necessary for each gallon in the complete system. So if there is a sump, count that in. There is a problem with the ‘weight system’ as live rock can be of differing weights, therefore when purchasing seek advice.

Similarly, when using a canister filter (or similar) for bio-filtration it is important to ensure two things – first that the canister can contain sufficient bio-media for the intended load and second that the flow rate through the filter is adequate. Manufacturers will advise the recommended aquarium size for canister filters, and media manufacturers will advise the suggested bio-loads.

Mechanical/chemical filtration is not so essential, so reading the media manufacturer’s recommendations is sufficient, if these types of filtration are required at all.

Stocking a marine aquarium without an adequate amount of bio-filtration will soon become obvious to the aquarist – sickly livestock and quite likely losses. Inadequate bio-filtration is likely to hit fish systems the most as they produce most toxin with their life functions. However, all systems require adequate bio-filtration, Nature’s free and essential service.

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The Canister Filter – A Thing Of The Past Or Still Useful?

Technology marches on and there are quite a few devices that are available for use with a marine system. The canister filter is not new and has been with us for a considerable period.

Canister filters are made by quite a few manufacturers. They are usually shaped, err, like a canister, though there are models available that are square. As time has passed they have become very reliable.

A canister filter could be considered a closed circuit. Seawater is delivered to the unit down a flexible tube, passes through the canister media and is then returned to the aquarium through another flexible tube powered by a built-in pump. It is best if the intake and outlet are at opposite ends of the aquarium, though perhaps this is not so important nowadays when the high flow rates within the aquarium are considered. Nevertheless, it is best to keep the intake and outlet apart.

What can the canister be used for? Biological filtration is the first use that comes to mind. Though filtration this way has been superseded by live rock an aquarium can still be successful using a canister, and many aquarists still do. The cost of live rock is high, and so canisters find a use. They need to be filled with a good bio-media, and this media needs to be protected by efficient mechanical filtration, such as sponges and filter wool. The cleaner the bio-media is kept, that is, kept clear of sediment, the better. The canister needs to be sized to the size of the aquarium, and the manufacturer’s specifications will include recommendations. One point about these recommendations – the flow rate advised by some manufacturers is often with the canister empty, when it is filled with media it will be less. Consideration can be given to using two smaller canisters so there is a backup. The canisters can be serviced alternately.

Cleaning the mechanical media in the bio-filter is important otherwise the seawater flow will decrease. It is a good idea to clean this media after two weeks. It may be that it remains reasonably clean in which case increase the period to three weeks and so forth. Sometimes it is recommended that the filter should be cleaned when there is a noticeable reduction in the flow rate. This is not really acceptable because for this to happen the media will be very dirty. By cleaning and checking the condition of the mechanical media the aquarist can arrive at a reasonable service period. A watch should always be kept on flow rates even with more regular cleaning because of the importance of bio-filtration – a failure or reduction could result in serious consequences. In addition, the bio-media itself must never be washed in tap water as this will kill the bacteria. If cleaning is essential then seawater should be used, and this can be at a routine change using the old seawater. The media should be very gently stirred with the fingers under the seawater to remove dust and debris. It will never look ‘as new’ but this doesn’t matter.

If the filter is used for bio purposes then the seawater leaving the filter will be low in oxygen. This is because the bacteria that carry out the bio-filtration function are oxygen hungry. The oxygen can easily be replenished by releasing the returning seawater at the surface.

There is an important point with bio-filtration in a canister filter. This is that the ‘Nitrogen Cycle’ will arrive at nitrate and stop. The ‘Nitrogen Cycle’ is the process where bacteria convert ammonia to nitrite, then the nitrite to nitrate. A watch should be kept on nitrate levels, though this should be done in any marine system anyway.

If other means of bio-filtration are in use then the canister is not redundant. It can be used for purely mechanical purposes, that is trapping detritus that is in the seawater. In this case only mechanical filtration such as sponge and filter wool are in use, and these can be washed under the tap. If they are showing any deterioration they should be replaced. This of course also applies to the mechanical filtration within the bio-filter.

The canister can also be used for activated carbon and/or anti-phosphate media. These are put in after the mechanical filtration. Certain anti-phosphate media types with a very fine particle size are usually better in a fluidized reactor, as in a canister they could tend to clog. Cleaning the mechanical filtration area is the same as above, and a note should be made of when the activated carbon and/or anti-phosphate media are due for renewal.

There is another use for the canister. If a small canister set up as a bio-filter is kept running on the display aquarium, or better the sump as connection is easier and the intakes/outlets will not be seen, then a permanently ready bio-filtration unit will be at hand. This is useful for those aquarists who have wisely used a small aquarium for quarantine purposes. This could be required again for quarantine of a new arrival, or as a hospital area for a fish with a problem. There isn’t a need to keep this aquarium full of seawater, but if required it can be filled and the bio-filter is ready.

So the canister filter is not out of date. Modern types are very reliable and much easier to service than the older models, which could be fiddly. Having a canister in the system could certainly be useful.

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Aquarium Filter Media – Is There Such A Thing As The Best One

The function of the filtration is to ensure that the relevant nutrients in the water are processed. These nutrients occur due to the inhabitants being kept in a closed environment – the aquarium.

Of course life in the ocean also creates waste yet the ocean is so vast that the waste/nutrients are controlled. Look at the oceans filtration – huge sumps, loads of live rock, the biggest deep sand beds ever, mangrove swamps etc.

In our aquariums fish and food are the biggest problems. As soon as you add fish to the aquarium there is a requirement for you to feed it. The trouble is the majority of aquarists unfortunately overfeed. Not on purpose I hasten to add feeding is a pleasurable time and as aquarists we all want to ensure that our fish are well fed.

Fish being fish though will just eat. This is a natural response and is primarily because they do not know when their next meal will come, therefore the gorge.

This causes the problem. There is a lot of food which does not get eaten and starts to decay, other food is passed through the fish’s digestive system either un-digested or partially digested as they ate to much, normal faeces plus urine.

Unless this waste is broken down and processed by the aquariums filtration system then before long the fish will be living in a nutrient loaded soup.

Not nice as I am sure you will agree.

This is why it is so important that a good filtration system is implemented. There are various types of filtration which can be utilised in the aquarium some of which are listed below:

• Canister Filter
• Internal Filter
• Fluidised Filter
• Plenum
• Deep Sand Bed
• Live Rock

In the above examples there are some of these which require filter media. Filter media can be many things – sponge, ceramic rings, plastic balls etc, however it can also be sand or even rock. For example the filter media used in a deep sand bed is the sand itself and the filter media used in live rock is rock.

There are a lot of people who see filter media as being something which is man-made which is added to the aquarium. It is of my opinion that filter media is anything where the required bacteria can function.

Any type of filter media can and will work. The issue is not about where the bacteria live it is how the filtration itself is maintained and how efficient the filtration is.

A good example of this is a sponge filter media. When the filter media is working efficiently the sponge will be clean and not clogged in any way, however over time the sponge if not maintained correctly will become clogged and the efficiency of the filtration will decline.

Another example would be live rock. If the live rock is not kept clean by either manual methods or by the introduction of a natural clean up crew then the filtration may not work at a level of efficiency which is could do if it was clean.

I do admit that there are some filtration media which does allow for more nutrients to be converted. The majority of filtration media finishes at the creation of nitrate. A deep sand bed, live rock or the two combined when maintained correctly will allow for the processing of nitrate as well.

Maybe the article should have been titled ‘Aquarium Filter Media – Which is The Most Efficient’ as it is of my opinion that there is no such thing as the best filter media…just the most efficient.

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Is There Such A Thing As The Best Aquarium Filter?

Filtration in the marine aquarium supports the number one requirement, and that is water quality. Whether the system is a fish only aquarium or reef aquarium, water quality is paramount. The next most important requirement is lighting for a reef aquarium.

The question here is a little too general. Are we talking of bio-filtration, or is it mechanical and chemical filtration? I don’t know what was behind the question so let’s have a look at them all.

Bio-filtration is the major filtration need in an aquarium, so let’s start with that. Bio-filtration is where the nitrogen cycle, or part of it, takes place. That is, bacteria take dangerous waste such as ammonia and nitrite and convert it. Without this natural service keeping a marine system of any type would be difficult, expensive and not so good for the inhabitants.

The major requirement for bio-filtration (at least the initial stages of the nitrogen cycle) is oxygen. So for anything to operate well this oxygen supply is required.

The first method with this in mind is the trickle tower, where water runs down with gravity through media. This is a good method of filtration, as oxygen is readily available from the atmosphere. The bacteria are not going to have any problems. The downside is that these filters produce nitrate and that point is the end of the nitrogen cycle.

So what about that old and well trusted method, the canister filter. These filters are very reliable and the modern ones are easier to service (this used to be a bind). The bacteria are completely submerged and depend on oxygen from the seawater, so it is important for the system designer to bear this in mind, that is the water surface should be open, and in addition if possible weirs should be incorporated, or a powerhead could be directed at the surface. Additional oxygenation may not be needed in a well designed system with correct water movement. Again, the end product is nitrate.

The under gravel filter is subject to the same oxygen considerations as the canister. However, the under gravel filter is, at least in my opinion, not a good choice because of eventual problems with media blockage. This filtration will not be considered further.

Though there are other bio-filtration methods the last one to be considered in this text is live rock. Live rock is natural in that it is nature’s product. The bacterial process in any filter type is natural of course, but live rock is natural overall. Live rock in sufficient quantity and of high quality can successfully filter an aquarium. A big plus is that this method can deal with nitrate if not abused – in other words, the filtration provides the full nitrogen cycle. That is a big plus. In addition, the very fact that it is rock means that the aquarist can use it to aquascape the aquarium, and it doesn’t matter if the system is fish only or reef. The bacteria again rely on the oxygen in the seawater, so the points noted about this are relevant.

It doesn’t take a detective to discover the champion bio-filtration system here, and yes, it is live rock. The downside is that live rock is expensive, and corners should not be cut to save money with this filtration. If money is a problem, then consideration to the canister and trickle methods can be given, remembering the point about nitrate.

Right, that’s that bit covered. What about mechanical/chemical filtration? There’s not much to be discussed here.

With this filtration the aquarist requires a method that is unobtrusive and reliable. There aren’t any oxygen considerations. The canister filter is the one, and ideal for the job. They usually have compartments where different media can go – sponge of various densities and other fine filter types to trap detritus, and carbon if used. As said, canisters are easier to service nowadays than they used to be and that is the main requirement – they should be regularly serviced and any carbon changed, and detritus trapping media cleaned or renewed. The cleaning can be under a tap, there isn’t any need for caution in respect of bacteria. (Note that this is mechanical/chemical filtration. If a canister is being used for bio-filtration then cleaning under a tap the media supplied for the bacteria is a no-no, as the bacteria will be killed with dire consequences.)

So there we have it, the best: live rock for bio- filtration and canisters for mechanical/chemical filtration. This is of course my opinion, but I would hazard a guess that there aren’t many who would disagree.

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What Is The Best Filtration Media To Use In A Canister Filter?

Canister filters have been around for decades. They’re usually shaped like a canister (strange that) but can also be square. The media sits in the canister under the ’lid‘, and it is in or on the lid that an electric motor is placed. Water to the filter arrives via a flexible tube, and is returned by the same method. Canister filters were used, and still are, by freshwater aquarists, and have been adopted up to a point by the marine hobby.

Canister filters are very reliable though some makes, as in most things, are better than others. There are a couple of points that need mentioning. The first concerns flow rates. It is the habit of many manufacturers to quote flow rates for an empty filter. Without the media in position the flow rate will be higher, so in the real world expect the flow rate to be perhaps up to a quarter or so less. Flow rates are additionally slowed by the lift – if a filter is placed on a level with the aquarium there is little or no lift, if it is below the aquarium the electric pump has to lift water from the filter to the highest point before entry to the aquarium. It is important to know this distance and check the filter performance from manufacturer’s data.

Ok, back to the media. The question could be taken three ways. What is the best media to use in relation to a marine aquarium, the best for bio-filtration, and the best for mechanical filtration.

As far as marine aquariums are concerned, the bio-filter media of choice is good quality live rock, in my opinion. Therefore the canister filter, using this as a “rule“, would be redundant as a bio-filter. There aren’t any rules, however, and though the canister filter is not the best bio-filtration method to use overall it is not redundant in this respect. Nevertheless, if live rock is to be employed, the canister filter is demoted to mechanical filtration.

If the canister is to be used for bio-filtration, then some care on the media set-up is needed. Bio-filtration is the ‘life support’ for the livestock and obviously is very important. Though it may be against some manufacturer’s suggestions, I have found that having all the mechanical filtration in front of the bio media is advantageous. I found a fine filter, sandwiched between two medium grade sponge filters, does an excellent job on protecting the bio media from debris. It is very important that the mechanical filtration is cleaned at regular intervals (the period dependant on the cleanliness of the water, perhaps every two to four weeks). In addition to helping to keeping the bio media clean, it maintains water flow. The bio media available is varied, however sintered glass, which is in the form of small tubes, seems very good. As there are lots of channels within the glass, it can act somewhat as does live rock for a while. In other words, nitrate can be reduced by bacteria. This benefit is usually not long lived however, as fine debris does inevitably find its way onto the media causing some clogging and the anti-nitrate advantage is lost sooner or later. (This media should not be used intentionally for any anti-nitrate properties.) The media still remains very good for ammonia/nitrite filtration. The media, if cleaning is required, should be gently cleaned in warm aquarium water, never in tap water. The latter will wipe out the bacteria. A final point to note when bio-filtration with a canister filter is employed, is that the unit will usually produce nitrate (perhaps not straight away as indicated). When nitrite has been converted to nitrate, the nitrogen cycle stops. If there isn’t a low oxygen environment for bacteria to inhabit, then nitrate will remain. A check needs to be kept on the level.

If the filter is to be used for mechanical purposes, then the same mechanical filter media as above can be employed. This media can begin with medium grade sponges, perhaps two layers, and end with fine grade filters. Many manufacturers provide ready made filter materials such as sponges so the fit in the filter is good. Manufacturers usually give suggestions for mechanical filtering. In addition, activated carbon can be used in the filter. It is usually placed after some mechanical media. Activated carbon is not always a necessity, and should not be used continuously if there is a need but periodically. The media removes trace elements from the water. When exhausted (manufacturers will suggest life expectancy) the media should be discarded, if more is required it should be new. Similarly, anti-phosphate media can be used. This can be used continuously if necessary, changing the media at the manufacturers recommended periods. Some anti-phosphate media has a tendency to clog and/or channel, making it far less useful. The types that do this are usually the ones with very fine media.

So the canister filter is useful to the marine aquarist. It is not ‘number one’ for bio-filtration, but can still be used as such, with success provided the aquarist maintains it properly. The filter is also useful for assisting in the removal of debris from the seawater etc. Some aquarists, having a canister filter available and not requiring filtration from it, have experimented with other media, such as small pieces of live rock debris and very coarse sand. I don’t know the results of these experiments, but I do know that in my canister filters using standard media, when doing maintenance I always have to remove very small shrimps and snails and return them to the aquarium.

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