hello, I change the filter monthly, i use Prime or AquaLife in every jug that I pour in the thank. My water testing was in my initial post but are, Ammonia 0, nitite 0, KH 3, GH 7, Nitrate 10 and pH 7.6. I acclimate all fish, float 10 minutes, add small amts. tank water every 10 minutes times 3...