I thought I would post a few pictures of a success story against the green monster. Unfortunately, I did not take pictures at every stage, but here are some before and after pictures.
Just as background, this is my in-law's first pool (they live close by) and they have had it for about 18 months. For the last 12 of those months, they have been fighting algae problems. They had gone through 2 different pool stores, bought tons of chemicals and were fighting a loosing battle.
After the last visit to the pool store recommended upping the powdered shock level to 18 lbs (and if that didn't work, they would need to go to 36) , I convinced my in laws to let me try the BBB method.
The green pool pictures are from Sat. June 1. The CYA level of the pool was > 100 and I decided (after asking on the forums) that we needed to replace 40% of the water to bring the levels down:
I also took the opportunity to pull the steps out (something I had been wanting to do, but had trouble convincing my in laws of the necessity). The giant leaf/muck monster had taken up residence under the stairs. I did not get any pictures of the piles of leaves we pulled out, but it was significant. I did get this picture of the sand bag the installation company used for the steps--you can see the algae in the bag:
After refilling the pool, CYA was still at 90, so I was shocking at >24. My cc at times was 9.5 ppm.
Flash forward a month (I did lose a week because I had to travel out of the country for work and my in-laws had trouble understanding the difference between the shock level and the normal level) and perhaps 100 gallons of bleach:
I have clear water, FC = 7, CYA = 50
I can say it got very frustrating because it seemed for days nothing appeared to be happening. I had a green/yellow/green soup and I was just dumping gallons of bleach into the pool for no reasons. But in the last 10 days, I started to see real progress (cc dropped to <1 ppm), a definite change to light grey and "passing" OFCL test . About 6 days ago, I started to add DE to the filter help clear the particles. Initially, when I would add the DE, the filter would load up in 2-3 hours, so I was back washing on a very regular basis. This plus vacuuming the pool every day meant adding water on an almost daily basis.
Thanks for all of the information from the forums. For anyone else battling algae, they are right. You need a good test kit, follow the pool calculator, buy way more bleach than you think you will need and be patient.