Confused About Canisters Being Nitrate Factories

[Natereef]

So as Ive scoured the net for information I akways read about how canister filters are nitrate factories. This confuses me. As the cycle works ammonia gets converted to nitrites then to nitrates. So the canister filter with bio media just converts the available nitrites in your water. It doesnt just magically produce nitrates out of thin air. So the nitrates that theyre producing would have been produced either way with your live rock.

Example lets just say you have 5ammonia->5nitrites->5nitrates. It doesnt just produce 20 nitrates magically. These are just example values.

So whats the real problem with canisters and biomedia?

Appretiate some answers so I can gain more knowledge for me to absorb. Thanks.

[Tom39]

I questioned the same thing a while back and could not wrap my head around what was the reasoning behind calling canister filters a nitrate factory. My thinking was that if properly maintained what was the difference between it and any other filters? So to satisfy my curiosity I hooked a canister filter to a 40b system I had up and running. When I say up and running I mean a fully cycled tank, that with proper husbandry is rock solid and has reached a point that it will maintain its equilibrium of parameters as long as you don't neglect the husbandry or overfeed.
For my test canister I chose a Fluval G3 and set my cleaning schedule at a weekly filter change/cleaning and monthly interior and node cleaning.
1st month no issues.- Nitrates about 1-5ppm
2nd month nitrates slightly higher - about 5-10ppm
3rd and 4th month gradual climb - about 15-20ppm
5th and 6th month - about 35-40 ppm

What I came to find is that even with a regularly scheduled cleaning the interior of the canister held debris that would remain. My conclusion was that this debris would cause a rise in nitrate levels and unless I was willing to go through the process of dismantling the canister and thoroughly cleaning it more often, it would continue to raise the nitrate level.

So IMO, what it boils down to is that canister filters become nitrate factories because of the amount of work that it takes to keep them clean.

But then again that is just my observation.

[don_chuwish]

They just need to be cleaned often, as do filter socks or any other filtration media that collects bio mass gunk. That gunk decomposes and returns nutrients to the water column. The advantage of a skimmer is that it removes it from the flow - unless you let it overflow the cup!

[Natereef]

I actually pressure wash my canister every week. Except for the media ofcourse. I hope it dont turn out bad.

[Happyschneider]

The canisters also lack any anaerobic low flow areas where bacteria can metabolise no3 further to nitrogen gas which then leaves the system into thin air.

Life rock offers this kind of filtration, as seems to be the case for marinepure.

Algae scrubbers take nitrates and bind them in their biomass. Which is easier to remove.

[OllieNZ]

Why not put live rock rubble in a canister?

[Sounds Fishy]

I use a canister in my sump ,as a carbon reactor.No filtration material inside.I run a sock on the output and change it every 2 days.

[Jscwerve]

I use one for my QT. All that I use in it are some coarse sponges and ceramic media that I keep in my sump until needed. Once QT is over I cleaned the media, bleach it and after it is all dry, throw it back into the sump for next time. If not enough time has passed to significantly seed the media I will use live rock rubble from my sump as the samesame.

I clean the filter every few days when I'm using it. I've yet to see any adverse effects. It only takes about 5 minutes.