Flies in the filter

[cichlidmommy]

I have 2 aquariums, one established, one fairly new. Both filters get these tiny little flies in them, and I have no idea why. I have cleaned them, but that doesn't help.

Any solutions to my fly problem?

 

[Dorkhedeos]

use the cover. if they still go in, there is nothing you can do about it, i have the same problem. gnats are attracted to still water