Even though we have the pool for 10 years, we have never figured the chemistry thing out. Its pretty frustrating because you think you are doing the right thing, but the water tells you that something is wrong.
Overall the water looks good, nice and clear. Not hazy or murky. The trouble is that the algae always grows back. Last weekend I brought a water sample to the pool store and explained the problem. The guy was very nice and told me that even before testing he will tell me that my alkalinity would be low. He tested it and of course he was right. I needed to add 15lbs of Alkalinity Balance Control. That day I also added half a quart of algae killer and 2 gallons of shock after I scrubbed the algae off the pool walls and floors. That was Saturday. 5 days later and the pool needs to be scrubbed again. Clearly we are not doing something right. I read through pool school again, but I am not sure what I am missing. I ran through all of the tests on my TF-100 and have the following results:
pool temp 74°
Tonight I put the other half quart of algae killer in.
I would appreciate someone educating me as to what I am doing wrong.