Opening pool with massive algea growth

[Watermom]

You might try vacuuming to waste since you have a lot of debris and you picked up a few inches of water with the rain. The less organic stuff in there, the faster it will clear up.

[TomDehoff]

added 3 gals of last night brought TC up to 22.5 CC 1.0 FC 21.5, this AM before the sun hits pool I had TC 11 CC 2.5 FC 8.5. Lost 12.5 PPM before the sun. Only lost 7 PPM all day long during the sun. The increase in CC has me worried. Should I add even more Chlorine? I calculated that I would need 5 gals to hit the breakpoint of 25 ppm with the CC at 2.5 ppm.

[BigDave]

I don't see a CYA reading - presumed 0 but no measure. Given the gret loss of FC, the CYA has probably been converted to ammonia / urea. I don't know if you really want to go to 25 with no CYA - what kind of pool do you have?
Yes, keep adding chlorine - it and sunlight will clear the CC and algae, keep it at shock, test as often as you can and bring it back to shock.

[TomDehoff]

CYA tested at Pool store at 12. Its an inground vinyl lined pool.

[Watermom]

There is no way a pool store can get a CYA reading of 12. That test is just too subjective and you actually can't differentiate values under 30. We see this all the time.

[TomDehoff]

The pool was opened with zero CYA. I tested for it. Before I realized about the degradtion of the CYA I was adding CYA by way of TriChorl pucks in a floater I made. So there could be a low reading of CYA. I have taken the Tricholr out while I battle. Todays readings are after adding 3 gals last night.

Last night after adding 3 gals

TC 19
CC .5
FC 18.5

This AM reading TC 16
CC 1
FC 15

Only used 3.5 PPM last night down from 7 overnight two nights ago and down from 12 from just one night ago but it was distorted by the 2" of rain we had that night. Still brushing every day and backflushing too. Making slow progress.

[aylad]

What she means is that there may be a low level of CYA in the water, but the black dot testing for it won't differentiate between levels of CYA less than 30 ppm.