RH Mom:

I guess what Ben's saying is ultimately your pool is your responsibility. There's very few problems that ONE of us hasn't seen before.

Right now it looks like you have 3 fundamental problems:
1. Is your filter working properly and, if not, can it be fixed or must it be replaced?
2. Do you have enough chlorine in your water to kill the algae?
3. Can you get the dead algae out once it's killed?

Everything else is (forgive me) a user-created problem. The pool store happily sold you stuff. You put it in. It got worse.

Draining is difficult and dangerous. The ONLY safe way to do a complete water replacement is Pocono's sheet plastic method. You cover the pool with a giant sheet of plastic. Put NEW water on top of the plastic while you drain the old water out from under it. When the plastic sheet hits the bottom of the pool, the water is replaced. This prevents liners and solid pools from floating out.