PB_Smith
Aquarium Advice Addict
In my view a canister filter can be taken apart and cleaned readily. I run two and I can totally clean one at a time. So I can readily remove all debris and keep nitrates low. I can run purigen or carbon or all sorts of combinations.
From my experience an ugf is not as easy to clean and remove debris.
In ammonia terms I don't think much difference. I have say 40 kilos of gravels versus say 7 kilos of ceramic biomedia.
I think it comes down to nitrates. If your nitrates are low with an ugf why change? If they are high with an ugf than a canister filter I would swap to. My thoughts on an interesting discussion.
So again, it comes down to maintaining the filter regardless of the particular technology.
You did bring up another good point concerning ug filters. My current salt tank is 25"x13" with an average 2" substrate bed which gives me a filter media volume of about 650" cubed, that is considerable more volume than can be realized in a canister filter, and I fear I would break my brain if I began to contemplate the actual surface area available to bacteria in that volume full of sand/gravel.
Nitrates are one of the main concerns in any filtration system. In saltwater it has been partially addressed via the use of "live rock" The only thing that live rock provides is deep crevices and structures that allow anaerobic bacteria to thrive and therefore aid in the reduction of nitrate. Certainly not some miracle nor a necessity, although it certainly is portrayed that way. all that is needed is rockwork with similar porosity.