I just added pool filter sand to my 5 gallon desk aquarium and it is also a little cloudy. I rinsed the sand quite well but I guess not well enough! Oh well, it should settle soon. I moved up to a bigger filter also so it should get the stuff filtered out. Now, I just have to decide if I want to use this for my 125 when I set it up. Going to be so much rinsing :-(