Canister exterior filter

[Tbone112219]

Looking for input on if it's good or bad to use an exterior canister filter on a 55 gallon tank?

 

[Rutrag]

In a FOWLR, it would likely be fine.


In a reef, unless you are very zealous with regular (probably weekly) cleaning, it's generally not a good idea. Canister filters are so good at mechanical filtration that they trap detritus and end up many times causing high nitrates.

 

[Phranque]

+1. Since this is in the Reef Aquaria section, I'm assuming this isn't for a FOWLR.

When a canister filter traps solids, the water flow is still moving across them, and as they decay, it contribute to the nitrates & phosphates in the system. There are healthy systems with canisters, but you must be very diligent in your maintenance routine & clean them on a regular basis without fail.

A much better option is a sump with a filter sock, a good quality skimmer, and a refugium. The filter sock catches course detritus the same as a canister, but it's MUCH easier to change out a filter sock every couple/few days rather than repeatedly having to tear apart a canister. A skimmer filters out much finer particulates and deposits them into a collection cup, thus isolating them away from the water column, and a refugium with some macro algae help consume excess nutrients to prevent algae in your DT.

If you can't do a sump, IMO your best option is a good HOB skimmer & regular pwc's, but you are at "that" size where a sump begins to almost become a necessity for a healthy system.