I've recently bought blue foam to fill my carts and it leaks every where, so much so I think it's flooding the atty! Am I doing something wrong?
You should insure that the foam is cut to the proper size so that it fits somewhat snuggly in the cart, but is not compressed too much. If it's too small to completely fill the top of the cart, it will leak.
The blue foam cart will hold about 10-12 drops on the first fill, then around 6-8 drops on each refill.
What type of blue foam are you using? The one most recommended is the aquarium filter foam, Rite size U. Available at most Petsmart stores.