I have an above ground rectangular 12,000 gal pool. The last couple of months of last summer I battled green algae. Before closing I added the max dose of algecide but I can’t remember if I added the extra chlorine. We live in SC and we had a warm winter. Now my pool is dark green, can’t see the bottom, it has inch thick algae all around on the walls where the water meets the walls, and floating leaves and scum/algae all over. Do I drain and refill? (We are on well water so not a big expense, prob cheaper than a ton of chemicals). My concern is that the algae will still be left in whatever water is left on the bottom and on the walls. Should I scrub it before draining? Run the filter for a while to get all the heavy debris and algae out first?