Milky water?

[jeep]

About 2 weeks ago I noticed a slight filmy substance on the top of the water in one of my tanks. Overnight the tank became so cloudy (milky) that I couldn't see my fish. Over 3 days I did 50% water changes, wiped down the glass and cleaned ut the filters. With every water change the water got a little clearer and then it just disappeared. The fish never seemed bothered and the tank is now crystal clear.

3 days ago I noticed the same film in 2 tanks in another room, and overnight the exact same thing happened and the fish seem uneffected.

The tanks look like they have pond scum on the water. They don't really smell bad but there is a mild odor.

All paramiters are normal...

Does anyone have any idea what this may be?

[Carol_Roberts]

Are you feeding frozen beefheart? I think it's a protein scum. You did exactly the right thing to get rid of it. Figure out the cause and feed less of it.

[jeep]

Yes I do feed beefheart and that's what I first suspected.

What's weird is how fast it spread and how fast it disspates. Just a guess is that it's a strange bacterial bloom that is not really dangerous. Sure is scarey though...

I've been very careful not to cross contaminate my tanks, but I may have slipped up.