Although some would say it is a waste of money to prevent algae growth over the winter since you are going to drain and do a new liner in the spring, if it were my pool, I'd do it anyways. I wouldn't want to be dumping a lot of algae-infested water in my yard and I wouldn't want to handle (during removal) a nasty, slimy green liner. Just my opinion. Bleach is cheap, so it wouldn't be that much money spent that you'll be dumping.