30000 gal DE filtered pool with trichlor pucks was fine for awhile. Over the summer started using about 6 pucks instead of 4 every week. After a few days of not replacing the pucks on the usual date. Algae started growing. I filled up the pucks to the usual level but the algae kept growing. I tried shocking it with powder (probably dichlor or trichlor) and it only got worse.
Went to the pool store.
Pool Store Test 1
CYA 60-100 can't remember exact number
Said CYA levels were caught just in time to prevent drain and they suggested to tone down the puck use so I reduced it to 4 and it was shocked a few more times with the powder and then added a few gallons liquid chlorine to no avail.
After awhile Went back to the pool store and got water retested
Pool Store Test 2
Acid D 3
Store recommended that I do a 3/4 drain. Person I was working with however didn't want it so I was left to attempt to elevate the chlorine level a couple times with liquid chlorine to no success. Added a few more trichlor tabs but then stopped. After a little while longer I revisited the store
Acid D 1
Store recommended that I do a foot drain then eliminate the algae with calcium hypochlorite shock then use chemicals to remove the phosphate.
Didn't do the chems but I drained about a foot and refilled. The filter was taken apart and cleaned but the pool was a basically left to sit for awhile longer. Did another retest at the store. Printout was borked for something so only a few results were relayed to me.
CYA around 100
phosphates not measured due to algae presence
Store said Either pH or alkalanity or something was severely messed up and needed to be readjusted with 14-20ish pounds of chemicals. Didn't get around to adjusting the ph but Went back and fully reassembled the filter and added DE. Drop test showed very little chlorine left. Bought 12 gallons of KemTek Liquid chlorine and added it overnight to pool. Next day pool cleared up. Stayed clear for couple days with me adding a gallon here or there then overnight went green again. Went back to store
Acid D 4
Latest recommendation is to kill off algae with so sort of sodium algaecide and calcium hypochlorite then retest then use phosphate removal chemical.
Was careful to always take water around foot deep and at least a night after any chems had been added except for the last test. Filter wasn't working for alot of the days though which might have precluded through mixing.