The white sponges, are they sorta pinapple shaped? If so they are quite harmless, and will disappear as your tank matures.

When you say red slime, are you talking about cyanobacteria? The is generally a red film that covers just about everything, spreads rapidly, but best controlled by heavy skimming and nutrient reduction. Do a search here for cyano and you'll find a lot of info and opinions.... think we all tend to lean to a natural cure and not using a chemical one.