Ok I have a 125 with an fx5 housing 2 BGJD 6 Ebjd,one jd, 5 tigerbarbs, and 8 loaches. There are two power heads in there as well, maxijet 1200 and a power sweep. My problem is my nitrates tend to climb pretty fast like 20-30 ppm in 3 days. I feed once a day, oh the biggest fish on the tank is around 3.5 in and the rest are from 1.5 and up. I do wcs on Sundays which are 50%. I only run bio max pre filter and matrix in The fx5 with batting. I have tried to keep plants but my loaches tear them up and so do the dempseys. Is there a way I can lower the nitrate levels to where I do a 50% once a week. Just a little concerned because I did my normal wcs on Sunday and cleaned the canister a bit , tested the next day and readings were ph 7.2, ammonia 0, nitrite 0, and nitrates 0. Two days later nitrates at 20-30 ppm . I would remove some of the foam in the canister but don't want bypass , are there other options I can take ?