Whats with the bad rap on canisters?

[Marino13]

I have been reading a lot of stuff mostly bad about canister filters. I am starting a new tank and have already purchased a fluval 404 for my 75 gal tank. It sure wasn't cheap. do any of you guys use them? Please enlighten me. Thanks

[irishjabba]

I have been reading a lot of stuff mostly bad about canister filters. I am starting a new tank and have already purchased a fluval 404 for my 75 gal tank. It sure wasn't cheap. do any of you guys use them? Please enlighten me. Thanks

I use a HOT Magnum myself, and have always been happy with it's performance. I use it mainly to hold carbon and for water current in the tank. A friend of mine uses a Fluval, and is definitely happy with it's performance, with the exception of having to hold it sideways to get it to prime.

I think that for most reef keepers, the issue with using canister filters are the following:
1) If not cleaned and maintain regularly, nitrifying bacteria can grow resulting in an increase in nitrates. Also organic material can collect in the filter media and also raise nitrates and possibly add to algae blooms.
2) Carbon is the primary media used in canister filters, and some carbon can leach phosphate into the system, which can cause algae blooms.
3) If a canister filter shuts down for an extended period, the inside of the filter can become anaerobic, and bacteria can grow in that enviroment whose biproducts can be toxic to fish and inverts. If this happens, and then the filter suddenly springs to life again, those toxins can be dumped into the main system.

That being said, those arguments don't deter myself or any of my reef keeping friends from using them. Basically, just make sure that you check and clean the canister filter regularly. Myself, I check mine everyday to see that it's running (when I'm giving a quick visual check on everything else in the tank), and then clean it every two weeks, changing the carbon once a month. This prevents 1 and 3 listed above from being an issue. As for 3, I just use a good quality carbon, and when I pick a brand to use, I just test the carbon for phosphate (as listed in The Reef Aquarium, Vol. 1 by Julian Sprung/Charles Delbeek) to make sure it's not going to add it to my system.

I personally love to use carbon 24x7 because it's an excellent chemical filter, and find that the most effective way to use it is a canister filter, which forces water through the carbon, not around it.

I've notice the knocking of canister filters too, but I've yet to really hear a reason not to use them, especially if you're maintaining them regularly.

Patrick