I'd hold your Cl where you are. If you have that much algae, you should probably vac-to-waste as much as you can. That will help clear the water a little faster versus brushing it up into the water - however stirring it up will help clear it too - but you will have to depend on your filter to get the dead algae out of the water.

RE: Polyquat - I don't think it would hurt to put it in now as well - but you could probably wait until later in the year to treat, and only have to do it once. I usually have to put a quart of polyquat in my pool about mid season. I always get this whispy green algae that I can't get rid of otherwise once it gets good an hot (Late July, Aug.). The polyquat takes care of it for the rest of the season.

Keep the filter running - I personally run my filter 24/7 all season long. It makes it easier to maintain Cl levels, and keeps the pool cleaner. Electircity in Kentucky is so cheap - only costs me about $10 a month more versus running 12 hours a day.