Opening pool with massive algea growth

[TomDehoff]

I had a CYA reading of 20-30 last fall at closing. Typically when I open up in the spring the CYA is 0 so I am assuming that is the case this year as well. I have the DPD powder test kit that was sold with the test you kit you used to sell via this site. But I have read where it can't test above 15 PPM so I haven't done that test yet. If I have CC what do I need to know.

[aylad]

The FAS-DPD testing that was sold with Ben's kit will test chlorine up to 50+ ppm. If you're using OTO, then it probably is bleaching out. I can't imagine that much chlorine in one pool being used up that quickly, even with a big chlorine demand due to ammonia that is often produced when CYA is degraded over the winter, like Watermom said in her above post. Go ahead and run your test with the powder and drops--that one is WAY more capable of testing high chlorine levels than any of the others.

If you have high CC, that's another indication that your CYA was degraded into ammonia and will help us better figure out how to advise you.

[Watermom]

If you are still using the DPD-FAS powder from one of Ben's old kits, it probably is no longer any good. You might want to order some fresh powder.

[TomDehoff]

Okay, I've gotten new test kits and here are my results as of today. Total Cholorine 14 ppm Combined Chorline .5PPM PH 7.4 CYA is 0 Pool has a greenish haze. have been operating the filter (its a sand filter) 24/7, have vacumed the dirt off of the bottom and brushed the sides. I read somewhere where that it wasn't recommended to run the water through the filter when there is a lot of algae but we did. Do I turn the filter off for a day or two and keep the chorline high and let the stuff settled out? and then vacum up to waste?

[aylad]

Yes, you definitely need to keep the chlorine high--until the green is completely cleared up and you are not losing any chlorine overnight (testing at night and again in the morning before the sun hits the pool). If you see the pressure on your filter rising, indicating that it's catching the algae going through it, then I would leave the filter running and let it do its job. If you see anything blowing back through the returns, or your filter pressure isn't rising, then I would consider turning the pump off, letting it settle, then vac to waste.

[TomDehoff]

Here are some test results from the last two days.

Evening day 1 TC 15 (didn't test CC but its been consistently at 1 ppm through this whole ordeal)
Morning day 2 TC 12.5 CC 1.0 Loss 2.5PPM during the evening.
Day 2 before adding the nightly dose; TC 5.5 CC 1.0 Loss 7 ppm throughout the day
Added 3 gals of 12.5% pool chorline
Evening Day 2 TC 23.5 CC 1.5
Morning Day 3 TC 17.5 CC 1.0 Loss 6 ppm overnight. (also had rainstorm and picked up 2" of rain during the night as well)

Pool is an in ground vinyl lined with 27,000 gals
Brushed pool last two nights and I can see a lot of debris get stirred up each time (especially in the deeper end )

Any other suggestions as to what I should be doing.

[chem geek]

If you're using OTO, then it probably is bleaching out.

Just FYI. OTO doesn't bleach out and can be used to test very high chlorine levels as it goes from yellow to orange to red. It may not be very accurate and there are no comparators showing the high FC level colors, but it will tell you whether you have a lot of chlorine in the water.

It is DPD that will bleach out. Even the DPD in the FAS-DPD test can bleach out, but you get a "flash of pink" when adding the DPD powder in that case so can just add more until the color holds at which point you titrate with FAS-DPD drops normally.

[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.