I don't really feel comfortable giving advice yet since I am so new to all of this, but I'm sure someone will correct me if I am wrong. I would first vacuum up what you can (vac to waste is probably best but you may lose alot of water depending on how much you've got in your pool). Also, a skimmer sock may help to catch the finer particles so they don't just filter back through again. I think I am having the same problem except I didn't backwash it in there. I added 4lbs of DE at setup and I think it may have been too much and the excess was going out the return into the pool. SLOWLY it's getting better after several vacuum sessions (have not vacuumed to waste yet ~ will use that a last resort). Good luck!!