I am just about to re-read Pool School, but I'm asking for a second opinion in case I should start on it right away. The very nice pool man who was here fixing the pump answered a few questions I had for him. He said our black algae looked so bad that we maybe should consider draining the pool and treating the walls. It is seriously so covered! Disagreements with my Pool Man (brother in law ) have kept our CYA far too low in my opinion, so I've begun to add CYA (while he's in the hospital) and actually see the results on my test strips (don't hate me). Pump is working better now that it's repaired, and the real heat hasn't set in yet but it's supposed to be in mid 90s Friday. I've been using Calcium Hypochlorite to shock it and finally got some chlor tabs that have CYA. While pump was off for about 4 days I tested and put in about 4 cups of CalHypo and we brushed as much as we could.