Ook I have a 75gal with one 5" Fahaka Puffer(temporary Tank). It's been running for about 4 months now with no problems and crystal clear water. Currently running a Rena XP2 and a HOB Rena Smart filter. Two weeks ago I did my weekly 1/4 water change and a few days later my tank turned cloudy. I have done two other water changes since trying to get it cleared up. Both filters are working fine. Not sure whats happening. There is only the puffer and a 5" pleco in the tank. I was thinking of going and buying a bigger filter if it doesn't clear up soon. Any ideas?