Ok so I set up my new picotope (thanks again!!!) but I'm not sure if I have the filter set up right: I have the white sponge first (closest to the water side), then the carbon, then the black sponge/netting (closest to the back of tank). Is this right? Sorry if I'm not using the right names for the parts, I wasn't really sure what was the biological sponge and the other names. There's a lot of foam in the filter and there's been some white/clearish substance that's been collecting on the bottom of the tank in my gravel. Is this from incorrectly setting up the filter? Is it dangerous for my fish?