For those who own a Fx5, how often do you open your canister up and clean one of the bio media baskets? My fluval has been running on my 125 gallon tank for one year now. I opened it once at the six month mark and cleaned out the bottom of the canister and changed out one of the three baskets. My nitrates normally run about 20ppm, nitrites 0. Should I be cleaning the inside more often?