foamy water in sump

[CleverName]

Hello all. I'm new to fish keeping. I have had a 96 gallon freshwater tank with 12 africans and two catfish established for about one month. I have done one 20% water change. In the last few days the sump has developed a thick white/tan foam. I have searched the forums, and have gotten some indication that this could be caused by overfeeding (decaying organics in the water), but I have not found a definite answer. I have been feeding flakes twice a day, enough to be eaten in a few minutes and also dropping 2-4 algae thins to the bottom of the tank. Too much? Other possible causes? Should I be worried?

[kveeti]

My first guess was decaying organics - this also includes fish poop. Plants? In any case, I would definitely step up the water changes - including gravel vacuuming. Do you have test kits and can you tell us your readings? If the tank's established (no ammonia, no nitrites) the nitrAte reading would be good to know.

[miguelitro]

I've been getting a little of the same and over feeding is the cause.
I've been purposefully overfeeding to build up my stock of guppies in my 10 gal to put some in my 100 gal. I personally dont concern myself with test and all that, I'm no Ph junkie!
i would recommend just feeding a little less and plants and snails sure help with keeping everything in balance if done right. i've found its not as hard as everyone makes it out to be...