IRahmatulla;700338 wrote: How fine is that "marine aquarium sand"? Is it sugar fine, or oolite? Sometimes with finer sand, if your powerheads are pushing sand around you will get a lot of particles in the water. How cloudy is it? Is it see through, or milky? Can you tell if it is a lot of tiny bubbles? What kind of filtration are you using? If you have overflow/ect, are you using filter socks? If you are using some form of HOB system, do you have a carbon pad in it? When you set it up, did you add the sand to the water, or the water to the sand? Any stirring? Also, you mention not having a bloom, or whatever. Maybe the UV light, is letting some form of bacterial bloom in the water column. I have never experienced this, but I have read. Did you add your CuC yet? How long have you been running those lights from the FW tank? Maybe I am overloading the quetions...