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CANISTERS (traditional) :

You probably know many of these filters under names such as Eheim, PEP, Lifeguard, Magnum, Fluval, Atlantis, Tech, and assume that they all fall in the same category. That is not the case. Some are meant to be strictly mechanical filters, others can be adapted to perform several distinct functions: mechanical, chemical, biological, even heating, or a combination of several of those. The latter is what we would like to strongly discourage. Segregate, don't combine. Keep all forms of filtration separate from each other.

We must also differentiate between the traditional canister filters such as the Eheim, Fluval and Magnum types, and the others mentioned. The former can be loaded, or filled, with varying types of products, each one of which is meant to perform a different function. The latter are more of a pressure type filter, excellent at mechanical filtration.

In fish-only tanks that was certainly a very appropriate way of using these filters; in Reef tanks, we would like to discourage you from doing so (combining several filtration methods).

Remember, we are trying to keep all forms of filtration separate from each other, and since we will be using a trickle filter (see biological filtration), if you use a traditional canister, you should use it as either a mechanical or a chemical filter, not a combination.

Let's review how to use them as mechanical filters. Refer to the last section in this chapter to check up on chemical filtration canisters. Canister filters have one great advantage : they can easily be opened and serviced. That is a boon ! The easier it is to clean a filter, the more often the Hobbyist is likely to do so. And cleaning the inside of mechanical filters often is a requirement, not an option, as we have already seen.

Fill your canister with any material that is available in your local area pet store, and that is meant to be used in a fine filter. Pack it in firmly, but not too tightly, lest you will restrict the water flow too much. Canister filters can move a fair amount of water, but their pumps do not usually take a lot of back pressure. Switch the canister on, and you will be mechanically filtering the water on a continuous basis. You can take water from the bottom of the trickle filter (sump), and return it to the same area, or you can return it to the tank directly, or to the top of the trickle filter. All three are acceptable. In-line mechanical filters are discussed later.

Many Hobbyists use filter floss, some use ceramic tubes such as EfiMech from Eheim (stands for efficient mechanical filtration), kordon's equivalent : BioMech, pads such as blue-white bonded ones, coarse gravel, DLS or copy-cats of the original, foam sponges (beware though that most foam is bio-degradable, and if it is not, it may have been treated with compounds you do not want in your tank), natural sponges (my favorite), crushed coral, small coral rubble, Efigross (grob) a fine mesh of green plastic marketed by Eheim, layers of untreated viscose, and a host of other materials (hobbyists are very resourceful in this respect).

Clean the filter(s) at least once a week, more often is even better. Do not worry about bacterial loss, mechanical filters are not meant to act biologically. That is not their purpose. In fact, more often than not, the bacteria that grow in mechanical filters that are not regularly cleaned, do more harm than good, and some even suggest (de Graaf, 1976) that they may be the cause of wipe-outs, in some cases (Shigella type bacteria).

Cleaning the canister, cum mechanical filters, involves removing all the material that you placed inside, and rinsing it thoroughly in fresh water before placing it back in the canister. Sometimes it even pays to use new material, e.g. in the case of filter floss. Some materials need to be scrubbed, others bleached. In the latter case make sure you rinse them several times to remove all bleach leftovers. Do not, if you can avoid it, use dechlorinators. I do not care for their use in Reef tanks.

In order to make this process as easy as possible, it is suggested that you use quick disconnect shut-off valves, on either side of the canister filter. This will allow you to take it out of service without having to worry about water spillage, except for the very little water that is between the canister and the quick disconnect valves.

Eheim, Fluval and Marineland make such valves, and there may be others. American made ones are as good as the imports, so my suggestion is that you save yourself the extra cost, as imported ones are usually more expensive, and not necessarily better.

The size of the canister should be in direct relation to the size of the system that you have. In most cases a Fluval 303, or perhaps a 403 for 55 gallon aquariums will be fine. This may be larger than what you expected, but you will benefit from the extra mechanical filtration ability that you will have. There are of course other brands; get the larger models if you can afford them, they will do a better job for you, as they hold more filtering material.

Eheim, probably the inventor of the canister filter, has recently introduced its 2200 series, very similar to the previous 2000 series, but with slightly more flow, and a normalized shaft. These top-of-the-line canisters are really good value for your money and hold up for years and years. I personally use Eheim 2217Us whenever I need canister filters.

Filter floss is, in my opinion, just about as good as anything else you can find on the market. It is easy to use, relatively inexpensive, and can therefore be replaced each time you clean the filters. Buy it in bulk.

Make a habit of cleaning your canister(s) at least once a week. Your system will greatly benefit from it. That is my experience anyway. And if, as suggested, you use quick disconnect valves, cleaning and changing will not be a chore at all.

Remember, the easier it is to clean your mechanical filter, the more often your are likely to do so, for the benefit of your system. I have said so for a very long time, and must remind you, that only when you first set up your tank, can you meaningfully influence this. Install all mechanical filters in a way that will let you reach them easily.

CANISTER FILTERS (special)

Special canisters can be acquired to mechanically filter the water. Two examples are the PEP and Lifeguard Systems. These units usually require some piping, unlike the traditional canisters which the Hobbyist can just plug them in and run. Their installation is, however, not complicated, and if you already have them, by all means use them.

Most of these filters (there are others besides the two mentioned) use some form of pleated bag, or pleated device, to increase the amount of surface area through which the water can flow and be filtered. The more surface area, the better the filtration, of course.

The bags can be used as such, or special powders (often diatomaceous earth) can be added to the filter, to step the filtration up to very fine levels, in this case referred to a micronic.

Cleaning is a little more involved, as these bags usually need to be bleached to remove the accumulated detritus. This takes more time and requires that you make sure all the bleach is removed, before putting the bags, or other material, back in the canisters. It is, actually, a good idea to have an extra bag or pleated cartridge around. Especially so if your local pet shop does not normally carry them.

Because of the way they need to be cleaned, the pleated bags or cartridges will wear out. Make sure that whomever you buy such a unit from, if you decide to include this in your filtering system, will also be able to supply you with replacements. Some dealers don't, or you may have to special order them.

Although this type of filtration can be very efficient, it is, in my opinion, not a necessary expense on the smaller Reef Tank. However, if you have such a filter already, it is recommended that you use it anyway. They are indeed very efficient at removing even very fine particulate matter.

Some units come with pressure gauges. This allows you to determine when it is necessary to clean the cartridge (pleated bag or other device) based on what the manufacturer suggests. Indeed, increased levels of pressure inside the canister are an indication that it is plugged, and needs cleaning. Retro-fitting such pressure gauges is also possible.

If you plan to use one of these units, make sure that the pump that you will be using can handle the back pressure brought about by these filters. Small pumps will not do the job. Again, most manufacturers suggest which pump you should use.

Because canister filters are very versatile, some brands are offered in various configurations, e.g. heater modules, chemical modules, and of course, mechanical modules. Lifeguard and PEP are two examples.

Unless you already have one of them, we recommend an alternative way of fine filtration; less expensive than acquiring such units. Use either a canister, or check the section on trickle filters to see how fine filtering can be incorporated in the trickle filter itself. In fact, ideally, this option should be provided in the trickle filter you should get, either as an easy add-on option, or already built-in.

Special canisters, such as the ones described, come in various sizes, and if you plan on getting one, match the size up with what is recommended for your tank. Better still, buy one size larger. It can't hurt the system, and if you up-grade to a larger tank, you will probably already have the right size canister, and save yourself the extra expense of having to buy a new one. You may not be thinking about a larger tank right now, but believe me you will at some point. Most Hobbyists do.

Servicing will require that you shut your pump down, as these filters are usually piped in-line with the main water flow back to the tank. In fact, some tanks' filtration consists only of a series of these special canisters. Such may be efficient, but in a Reef set-up we do not recommend that you use such filtration as the only means of maintaining water quality. They can, as we have seen, be used as add-ons to the trickle filter, especially for mechanical and chemical filtration.

Shut-off valves should be placed on either side of these units, to allow for quick and easy opening and servicing. True union ball valves are probably the easiest type to use. Quick-disconnect shut-off valves are another possibility, and for most Hobbyists a less expensive way to go.

Piping in a by-pass line may be a worthwhile option, as it will allow you to service the filter without having to stop your system. To check how this is done, look at the drawing, a few pages ahead, in the section on molecular absorption filters and micron filters.

These type of special canister filters are often used in swimming pool and similar installations (e.g. spas). When shopping around for one, check your local pool places too. You may be able to get yourself a bargain. If you need fittings and plastic pipe, check the hardware stores, the do-it-yourself stores, and best of all, the local plumbing supply places. If you run out of options, U.S. Plastics, also called Industrial Plastics, in Lima, Ohio, sells by mail and has excellent prices.

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