Please help me with my problem of the pool.?

I have a large pool of 50,000 gallons above ground. For some reason, I'm having a problem algae this year. I should mention that I live in Michigan and was an exceptionally hot summer. I am the great content chlorine, 7.5, as recommended by the supplier of the pool. He added killer algae were surprised, and did everything I said. Covering the pool deck. What am I missing?

I have a pool company.If first walls has a brush algae problem and add algaecide bottom.next walk to the pool, pour a little closer to the pool skimmer pump.let run 24 days later hours.next wash vacuum filter pool. (New Position the filter filter filter) and then add chlorine.this should solve your problem. Ps indoor pool is not your problem. let me what happens

Solar pool heating follow up