My turn to tackle algae

If you're holding chlorine overnight, then go ahead and start raising your CYA. We typically recommend that people start with a target of around 40 ppm, and then once that level is reached, you'll need to evaluate your chlorine loss during the day to see if you want to go higher. You can add it through the skimmer and let it dissolve on your filter, but if you do that you can't backwash the filter for 4-5 days or you'll just wash the CYA out and have to start over. Or you can put it in an old sock and hang it in front of a return while it dissolves. If you're still needing to backwash to clear up your pool (which you shouldn't do until you see an 8-10 psi rise in pressure--remember that a dirty filter works better than a clean one..) then I would go that route.

Edit: Ben is apparently typing faster than me today........

I can finally see the bottom! After I confirmed I was holding Cl level overnight, I shocked the pool, let it circulate for a while and shut it down to see if I could get the cloud to settle. After three days, the cloud didn't change much, so I decided to floc.

After reading another thread, I was comfortable using alum. I read the directions carefully and consulted my father in law who is also a pool owner and retired water plant engineer. I dissolved the alum in water and added to the skimmer. Let it recirc for an hour and shut it down. I collected a sample in a glass to observe the floc in action.

By the next morning, the water in the glass had flocs on the bottom and a few flocs still suspended in the water but no fine particles. I still couldn't see the bottom of the pool but I knew I had a lot of sediment. I vac'd to waste and got a lot of sandy particles off the bottom. After a thorough vac, I vac'd through the filter. I picked up more stuff and then had to backwash the filter. I still couldn't see the bottom clearly but I could see the head of the vac through the haze.

Another vac the following day but no need to backwash. Still couldn't see the bottom clearly By this morning I could see the detail of the liner on the bottom. The filter gauge has shown an increase in pressure so I know it's working. I'm hoping for crystal clear very soon then I will adjust my CYA.

Thanks for all the help and information. POPP is the most important tool for success

I'm interested in how the alum works out for you. We need to use flocs more, but to do so we need to know more.