Whats clouding up my water?

[bradleyheathhays]

Have a 125 gal tank I'm selling and to show it's not leaking to prospective buyers I've filled it with tap water about 2-3 weeks ago and have done nothing else. Just in the past couple days the water has become cloudy and I'm not sure how to address it. History is this is a clean tank just filled with regular tap water that becomes cloudy 2-3 wks later. Any advice on what I can add to the water to clean it up?

Thanks

 

[Brad M]

First of all are you from northern Illinois I may be interested. Lol

Do you have the filters or lights running? If the waters stagnant that could cause it.