I had that happen too. For 2 years I had a 25 gallon eclipse with those white specks. No matter what I did they would not go away. several times I cleanned out the whole tank and still they were there. I even tried buying water from LFS. Any and all fish I would put in there would get sick and I would have to transfer to one of the other tanks where they usually would get better. The only fish to ever survive was a pleco.
After 2 yrs I gave up and sold the tank for 40.00 (replaced it with a 55g).
After 2 yrs I gave up and sold the tank for 40.00 (replaced it with a 55g).