green slimy algae or whatever it's called

[Bifferwine]

I recently had a problem with high nitrates too. I was doing 10% water changes every other day for about a month until they got down to an acceptable level.

I would recommend running some phosphate removal media like PhosGuard or PhosBan. Something like that. You can place it anywhere in your tank where water is forced through it, like in a canister filter or some skimmers have a compartment for it. Alternatively, you could purchase a phosphate reactor to put it in -- they're cheap, less than $40, and very useful.