Canister Filter for a Reef tank


So I was at my local fish store today and I was talking to the owner about reef tank set ups. He told me that canister filters are not a good thing to have for reef tanks because they hold on a lot of crap and then spray it all over the corals after you clean the filter. I have noticed a little bit of stuff coming out after cleaning but not much. So in your opinion, yes or no on the canister? If no what should I replace it with?

Absolute no on the canister filter. They don't really do much good unless you clean it every 2 or 3 days, maybe even less. When I took out my canister filter, my nitrates dropped from 80 to 20 within 3 days. I suggest you rely on a good skimmer and live rock for filtration. A sump with a refugium filled with with macroalgae such as chaeto or caulerpa would be a huge bonus, as the plants will take up the nitrates and you can harvest the plants so that you remove the nitrates and phosphates from your system.
Sweet, thanks for the info. So should I just do a powerhead type filter and a protein skimmer? I am considering a sump but I am very limited in space and funds. Also I do not have one yet for my 55 gallon which is just going to be live rock and fish but I was considering getting a canister filter. Should I abandon that idea as well?

And I am from the Baltimore area, Jml
Last edited:
The biggest problem with canister filters is that it traps excess food and waste material in the chamber where your cleanup crew (CUC) will not be able to reach it.
This would lead to decaying materials producing more ammonia in the tank and thus increase nitrate levels.

Without a canister filter, your cleanup crew will be able to get to the excess food and dispose of them before they decompose.

Also, since there is no canister filter that traps excess food, it will be much more obvious if you are overfeeding.
The extra food will continue to float around in the tank instead of causing the illusion that the tank is clean but in fact the food just got trapped in the canister.
I am using a canister filter (Fluval 205 for a 24 gallon tank) and can not wait till I get my new tank with a sump and skimmer in a few months.

The canister can be good but it takes a lot of maintenance to keep it clean and if you don't the water quality can decline very quickly.
Thanks everyone for the information, ok so I know its a no go on the reef tank but what about a tank with just fish and live rock? Also how is a sump different form a canister filter?
I see you're getting confused. Check out hang on the back (hob) protein skimmers. You do not need a sump to have a protein skimmer. A sump is merely a second tank that is connected to your main tank. You can put a skimmer in it and your heater. It's not necessary to have a sump. I do not. I just have a hob skimmer on my main tank.
Having a sump lets you have a place to put equipment so that it isn't in your main tank. Again, nice to have, but, not necessary. You will just use a different style of skimmer on your tank if you don't want to have a sump.
So is the main purpose of a sump just to increase water volume and hide the equipment?

Water volumn, hide equipment, more lr(biofiltration), refugium. Sumps have open tops, canisters do not. It seems like every post is about having a canister lately, just check some of them out too, they all say the same