I have two 10-gal
. tanks more populated than yours, and only do 2 gal
every week. My skimmer is producing just fine. I am not familiar with your filter, but I have a Skilter250 on one of my tanks (Bio-Wheel filter on the other). The only thing I don't like about it (besides the noise) is that it dumps millions of micro bubbles in the tank. I haven't been able to find a way to stop that without changing the way my skimmer skims.
I agree with the others in that 40% WC
is not necessary for your bioload. Do you have a DSB
? How much LR
do you have? Those can really help with the filtration as well.
How old is your tank?
Here's a thought if you cut back on the water changes and still get no skim:
If the tank is fairly new, maybe it was skimming before because of the inballance in water quality; but now that it's older the water quality has stabilized, so there's nothing much to skim anymore.