I seem to be losing a fish a day and I don't know why. I'm running two canisters and a wet dry. I tested the waters the last few days and my ph and hardness are normal (don't remember the exact numbers but there the same as always). Ammonia is 0, Nitrite is 0, Nitrate is barely noticeable. The tank is 120 gallons, gets a daily 7-10 % water change at noon every day. No bloating, no ich, fecal matter is normal color, no lack of appetite, no new fish, temps holding at 78, no new anything. maintenance has always been general, ill admit the sand could stand to be vacuumed but still there isn't a noticeable amount of deitrus. I thought maybe someone turned on them but the biggest meanest fish was the one to go today so now I'm lost.... i upped the water change today to about 25% to be on the safe side. any ideas?