I am guessing its too much protein in tank causing this. Tank has been running for about 10 months, never a problem. The only changes to the tank is I recently added some Seachem Matrix to my HOB filter. The foam started about a week after. Not sure the Matrix can cause foaming, so not sure what else could cause it. Everything else has been pretty constant. Took some fish out, added a few more back, numbers are about the same. Might be feeding a tiny bit more. Going to skip a couple of feedings a week and add an extra 25% wc mid week from my normal 50% wc once a week. Ideas.