the polyquat is the only algaecide we recommend around here, and it's what several of our forum members use to treat their water before closing for the winter. It will help deter algae from forming due to low chlorine levels. If you treat it with polyquat, run it for a few hours, then chlorinate back to your normal chlorine level, then cover the pool, I think your water should be in pretty good shape when you come back.

Clearing up algae entails adding enough bleach to get your chlorine up to 15 ppm and holding it there until the pool clears, running the pump and filter 24/7 until it clears up,cleaning your filter as your pressure indicates. Usually takes a little longer on an intex pool because the filters are often undersized, but with a lot of bleach and patience it's not a huge deal.