Originally Posted by Bectan01
Weekly maintenance is almost mandatory on a salt tank anyway with water changes so if you're doing that then do the canister at the same time. Check out some of the articles on here about salt water maintenance and upkeep, there are many differences between salt and fresh (forgive me I've never kept freshwater fish) and I believe that the reason why canisters are great for fresh and not so for salt is because of the way the beneficial bacteria live. In salt the BB live in your live rock and sand and canisters can trap nitrates (bad - hence regular cleaning) I believe the good BB in fresh live in the canister but I could be wrong! Perhaps someone who knows a bit about both can clarify?
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Seems there are a few misconceptions here.
BB bacteria live on ALL surfaces in the tank and filter media.
ALL filter types have the potential to become "nitrate traps".
In reality one issue is that the aerobic portion of the process occurs much more rapidly than the second part, breaking down nitrate.
So the more efficient your aerobic portion is, the quicker it will produce nitrate.
How canisters and similar become "nitrate factories" is because they have no means of actively removing the dead bacteria and it is that dead bacterial film that helps add to the nitrate problem. Fluidized bed filters (reactors) solves that problem.
Any type of filter has the potential for the same problem if not maintained regularly.
"Live Rock" is simply rock, preferably very porous, that has been colonized by beneficial bacteria, and sometimes other organisms. "Live Rock" also is present in all freshwater aquaria and is not exclusive or unique to salt water.
If you are going to use a canister filter for biological filtration primarily, you need to make certain that the water entering it is as free of particulate matter as possible. That will greatly increase the efficiency of the biological media and reduce the need for cleaning a bit.
Basically you want the end result to be 0 products of the nitrogen cycle, especially nitrate & phosphate if keeping corals.
The best way to achieve this is by removing as much organic matter as possible first, so the first stage of filtration should be two part mechanical; filter socks/media that filters down to at least 100 microns then from there to a protein skimmer.
After mechanically removing floating/dissolved organics further extraction can be made chemically using carbon or my new favorite, Purigen. Works great in a reactor.
That about covers removing organics from the water, now the biological portion takes over. So after mechanical/chemical it should proceed onto the aerobic BB portion, however you want to achieve that, bio-balls, ceramic noodles, Matrix or lava rock, the last two being my preference due to the enormous surface area available for both aerobic and anaerobic bacteria.
Then from there into a media reactor designed to contend with nitrate and phosphate or into a refugium if that is the direction you go.
Simply put, you want to remove all solid matter and as much dissolved organics before the water gets to the main biological section so that there is less organic waste to be broken down which ultimately results in less nitrates accumulating.
It's all really simple when you break it down into stages, the tricky part is deciding amongst the tons of extortionately overpriced, mechanically simple equipment out there.