I've got a greenish/yellowish dust all over the bottom of the pool that brushes up quite easily, but makes the whole pool look green. It appears to be mustard algae. I just found this board, so I'm eager to stop wasting money at the pool store. My first attempt was to shock the pool with 2 bags of powder shock (10,000 gal per bag), then use a product called Yellow Out which I have had success with in the past. That didn't work, so I went back and applied 4 bags of shock and a product called Suncoast All in One Algaecide. I first added the 4 bags of shock, waited a day and then added the algaecide and let the pump run 24 hours. Followed by 2 more bags the next day. I brush the pool twice a day to remove the dust.
I'm not having much success. I replaced the Cartridge filter at the end of last season, so it is pretty new and I maintain a filter pressure of about 20psi which is the recommended level. The pool store is too expensive to keep dumping in chemicals that aren't working.
As a followup question, here in Florida, it tends to rain in a large burst and then go away. My pool can fill up an inch or more on any given T-storm. This tends to start the algae process. I have a Chlorinator that I keep 5 cakes in that is usually set to 4/5 and maintains a good chlorine reading, however these storms seem to overwhelm my system. Should I toss a bag of shock in when a storm rolls in? Anyway to avoid this?
What are my next steps?
I have a 19,000 gallon, gunite - white, Cartridge filter, chlorinated pool (no salt).
FC - 4.0
CYA - 60
CH - 600 - This reading was weird because I went to two pool stores and one told me it was 280 while this one said 600.
TA - 120
pH - 7.5