Help to maximize C4 filter capabilities?


I know I am probably over stocked at the moment or will be soon enough...36gallon tank with 5 very small cory cats, 6 tetras, and 6 young electric blue acaras

I have a fluval c4 filter currently with the foam/poly pad as mechanical, zeo-carb for chemical, and c nodes for bio.
However, my tank ALWAYS reads 0.25 or ammonia using apI master kit. I never have nitrites all while I rapidly produce nitrates.

I am looking to see what I can do to gain better control of the nitrates.

I have already order seachem matrix, purigen, & matrix carbon. I plan to shove the 100ml bags of carbon and purigen into the C4s chemical basket and also add a bag of matrix here. Eventually the cnodes in the trickling chamber will also get replaced with more matrix but not yet obviously.

I also order a filter max 3 to attach to intake tube for better prefiltration. Plus I plan to add a 50 micron polishing pad behind the existing foam/poly pad.

Thoughts, comcerns, questions, or ideas??


  • Thread Starter


Apparently its not uncommon for people to always have a trace amount of ammonia between 0-0.25 using the API test kit. I am obviously cycled with the nitrate production. I mean if you think about it, its not like ammonia is "immediately" removed as fish produce it. So if you have a pretty full stock it makes since that you my have trace ammonia. However it bugs that's why I am here.


I'm running a C4 on a 20gal high with 2 guppies, a BN pleco and 7 corys (ambiacus and/or brevirostris) and always have zero ammonia and nitrates. I might see the faintest discoloration to the ammonia test, but it's so small that I effectively ignore it. Tank is low-tech well planted as well. Nitrates never go above 20 before my weekly water changes.

I am running the original foam/poly pad with the poly pad removed, Matrix in place of the carbon and the c-nodes. I've tried with and without a 100 micron pad behind the foam and to be honest, I can't tell a difference aside from having to clean it every 3 days with. I'm finding the filter pushes a lot more water through without the 100 micron pad and the tank is actually more clear (go figure).

The other thing I notice is the C4 generates an enormous amount of "bio-slime" inside itself very quickly compared to the QuietFlow 20 on another tank of mine. Maybe it's just because it's translucent and you can see it easier, but I'm amazed at how much "gunk" I rinse out during my weekly rotations of rinsing the various media.

Aside from the dribble pad/chamber being a bit of a gimmick, IMHO, I really like the filter. Very easy to service individual media, quiet, and customize-able for a HOB.


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