I have been having problems with my 180 for weeks now .my watetr is always cloudy. I HAVE BEEN DOING 30% WATER changes every 5 to 7 days . have a wet/dry system with a 40gal sump icant remember the pump size but it was more than what was needed.ph 6.8 0 nitrites 0low nitrates .tank has been cycled for about 6 months. any ideas