What's the bioload from common "pest" snails?

Man, this is weird. I'm doing another water change, and I took my filter apart just to see if anything's going wrong in there, and every surface in my filter is coated in a thick white film. It's like the normal sludge that forms inside the filter, but instead of being a greenish brown, it's white and kind of pasty looking.
The betta seems totally unaffected by all this, but I guess I should get him in a bucket.

I have a new theory--I think I had some kind of major snail die-off in both tanks. Visibly, there are way fewer mts than there used to be. The dead snails are causing the ammonia levels to rise, and the ammonia is causing a bacteria bloom. I think the white sludge is part of the bloom.
I don't know what else to do besides keep changing water and try to pick out any dead snails that I see.
 
AquariaCentral.com