Serious algae proble

[Guest]

We just moved to a house with an above ground pool. They did not cover it over the winter and the algae is horrible! I have shocked it 2 or 3 times, can't remember. I put spot kill in it twice. Today I shocked it, 4 bags and the spot kill and it is still black. I brushed it the best I could, since I can't even see what I am brushing. I also backwashed it twice and the water is green. I wanted to backwash until it ran clear, but the water is so algae ridden it won't run clear. Plus the pressure guage on the sand filter reads 18-20. Is that bad? How can I get my pool clear and ready to swim?

[John B.]

Instead of shocking the pool with bagged product, get some liquid chlorine and super clorinate the pool. Cirrculate the water for at least 8 hours then shut off for about 8 hours letting the dead growth settle to the bottom. Vacuum to waste instead of back wash. If the problem is as bad as you are describing, you may have to eventually drain the pool, acid wash the surfaces and refill. The liguid chlorine will work better than algicides. Most commercial algicides are for maintenance and not really perfect for eliminating your problem. Also, adjust the pH to 7.2 to optimize the effectiveness of the chlorine. Best of luck. I hope it works for you.