Can you use a salt water tank for fresh ...

[gordruls]

Can you use a aquarium that was once used for salt water, for fresh water fish? I have had 2 that about 2 months after set up the water gets foggy and I can't seen to get it clear even with major filtration. Or the question should be how do you get cloudy water clear in a fresh water tank?
I tried to keep the lights off for days to see if the problem was algae...No change.

 

[mandarin w]

There is no problem useing an old saltwater tank for fresh water. Just give the tank a good cleaning, maybe use vinagar to wash every thing down, let it soak for a day and rinse it out well.
The cloudyness in the fresh water tank may have something to do with how you set it up. Did you rinse your gravel well, did you let it cycle before you added fish. What are you amonia, nitrate, nitrite and ph levels, use fresh water test for your testing. But it sounds more like an amonia problem or the tank wasn't cleaned very well.