| The canister filter has been in use for decades. | | | | others. |
| Freshwater aquarists were the first to make use of | | | | The canister filter is cleaned at least every four |
| them and they still do. Then along came the marine | | | | weeks, or as experience dictates. The coarse/fine |
| aquarium and the canister filter was employed to | | | | filter material must be kept free flowing and the |
| support those to. Canister filters have been around | | | | biological media protected from dirt. With two |
| for so long that they are now very dependable and | | | | canisters, this can be achieved by cleaning one at |
| failures are rare. | | | | two weeks, the other at four weeks, the first at six |
| Aquarium filtration techniques have progressed | | | | weeks etc. The biological media is not cleaned, just |
| considerably in the last decade or so. Aquarists strive | | | | the coarse and fine filter materials. It goes without |
| to make their reef aquariums dependant on natural | | | | saying that the canister filters should have the |
| filtration as far as possible. The use of 'live' rock is | | | | correct capacity for the aquarium size they are to |
| the major example. This rock can support the reef | | | | support. |
| aquarium wonderfully, provided it is of sufficient | | | | Ah, I hear the question coming up! But canister filters |
| quality and in sufficient quantity, and its capabilities | | | | are just nitrate factories aren’t they? Nitrate in |
| are not abused by the aquarist. Live rock is probably | | | | excess is one thing the marine aquarium doesn’t |
| the number one filtration method in use nowadays, in | | | | need. |
| reef aquariums anyway. Another example of filtration | | | | Up to a point that is correct. A canister filter is a |
| is the DSB (deep sand bed) where natural methods | | | | nitrate factory. But the production of nitrate is not |
| provide support. | | | | exclusive to the canister, it is produced by any |
| So what of the canister filter? With all these modern | | | | biological filtration system. Another filtration system |
| techniques perhaps the need for a canister filter is | | | | will produce the same amount of nitrate as the |
| gone. Well, no it isn’t. | | | | canister with the same amount of ammonia to start |
| A canister filter can be used to house activated | | | | with. It is the nitrogen cycle, the natural breakdown |
| carbon, or filter pads or wool, to assist in keeping the | | | | of toxics. There is a difference however. The |
| seawater pollutant clear and dirt free. Some aquarists | | | | canister filter is having oxygenated water pumped |
| have put chunks (around ½" to 1? square) of live | | | | through it, which means that the nitrogen cycle can |
| rock in the canister and report that the life within the | | | | only progress as far as the production of nitrate. Live |
| canister is quite surprising - tube worms, tiny shrimps | | | | rock, for example, will hopefully complete the full |
| etc. | | | | nitrogen cycle, breaking down the nitrate into gas |
| However, is the canister filter finished as far as a | | | | that is released from the aquarium. Routine seawater |
| prime biological support function is concerned? No, it | | | | changes are recommended for all aquariums. Where a |
| isn’t, is the answer (in my view). It is not the | | | | canister filter is in use (for biological purposes) the |
| number one recommended marine biological filtration | | | | seawater change must be completed as it is one of |
| method nowadays, and rightly so. There are | | | | the methods for reducing nitrate. The aquarist using a |
| occasions though where the use of a canister filter is, | | | | canister can consider completing the nitrogen cycle |
| what shall we say - convenient. | | | | by other means. A denitrator will remove nitrate |
| Live rock is very expensive, and there is little point in | | | | efficiently, so that is an option. Sulphur denitrators are |
| deciding to filter with it if sufficient quantity is not | | | | the best option (in my opinion). |
| obtained. There are other decorative and marine | | | | Now things have become more complicated again. If |
| suitable rocks that have no filtration capability, but | | | | denitrators are to be considered then, coupled with |
| are available at a far lower price. So the aquarist who | | | | the cost of non-live decorative rock, and the canister |
| finds the cost of live rock prohibitive is still able to | | | | filter(s), plus the bio media, the cost is rising. The |
| consider a marine aquarium. Decorate with low cost | | | | option for a canister filter seems only sensible when |
| rockwork and filter with a canister filter. There | | | | a smallish aquarium is obtained (for example, |
| isn’t any need for a sump, another cost | | | | seawater changes are more manageable and less |
| reduction. | | | | costly). Larger aquariums seem better with live rock |
| I can nearly feel the hackles rising on some marine | | | | even though the overall cost is high. |
| aquarists! But lets consider it further. | | | | This is not a recommendation for canister filters over |
| The low budget aquarist should, if finances allow, | | | | other filtration methods. It is my opinion that live |
| obtain two canister filters, though this is not | | | | rock, coupled with a DSB in a sump, is a very good |
| absolutely necessary - canister filters are reliable as | | | | filtration option. However, for a smallish aquarium |
| stated. One acts as a back up for the other. The | | | | where water changes are not a problem and the |
| compartments inside should contain coarse and fine | | | | bio-load is not particularly heavy, the canister filter |
| filter material (the coarse before the fine). Following | | | | remains a viable biological support possibility. The |
| the filter material, and last in line, should come the | | | | aquarist should, of course, cost the options very |
| biological media. This is easily obtainable and not too | | | | carefully, and use live rock where possible. |
| pricey. Sintered glass media is good, but there are | | | | |