Opening pool with massive algea growth

[TomDehoff]

I have opened our pool and it had a lot of algea growing it in. The pool is 27,000gals vinyl. I added an initial dose of 20 gals of 12.5% Liq chlorine which figures out to roughly 90 PPM and this AM I tested with the OTO test kit and a zero reading of cholrine (clear no color at all) So we put in another 12 gals which should be roughly 54 PPM and again I have a zero reading on the OTO test kit. (clear no color at all). I have never put in this much chlorine before and I just wanted to make sure that there is no way I have put in too much chlorine that its fooled the OTO test kit.

[Watermom]

Do you know what the CYA reading was when you closed it last fall and have you checked the CYA this year? Many times over winter, you have bio-degradation of CYA into ammonia and it can take massive amounts of chlorine to get rid of it. I can't imagine that after that mega-dose that you had none this morning though. Do you have a it that can measure a CC (combined chlorine) reading?

If you don't have a good kit, you should get one. The one we recommend is the Taylor K-2006 or 2006C which you can get through the test kit link in my signature below. You're gonna need it because most kits can't read chlorine levels as high as you'll need to clean this up.

Welcome back to the Pool Forum!

[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.

[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.

[TomDehoff]

Update for today; Added 3 gals last night ended up with the following readings. TC 18, CC 1, FC 17; This AM had TC 15, CC 1, FC 14. This is the forth day of 3 gals/day chlorine addition. Is this normal in the battle to clear up the mess from the degradation of the CYA over the winter??? Been losing 3 to 3.5 ppm overnight the goal is just a 1ppm loss correct?

[BigDave]

Sounds pretty normal. It taks alot of chlorine.
Stay at it, the fact that you're losing FC overnight and have a significant CC level indicates you're battling something.

[TomDehoff]

Would I help the cause by upping the dose to 4 or 5 gals overnight? That would be roughly 25 to 30ppm vs. the 18ppm that I am adding with the 3 gals? CYA is very low 10 or less.

[BigDave]

I'd be concerned about bleaching your liner. Can you dose an extra gallon in the morning?

[TomDehoff]

I could do that.

[TomDehoff]

Back with today's numbers. Last night after adding 3 Gals TC 19 CC 1 FC 18, This AM TC 14.5 CC 1 FC 13.5, Lost 4.5 ppm overnight. Pool is noticeably clearer today, the sediment that was stired up with brushing last night was the least amount yet. Its getting close to being finally cleaned up. I added 1 gals this am after I took the sample to keep the FC high during the day hopefully it helps.

[CarlD]

Back with today's numbers. Last night after adding 3 Gals TC 19 CC 1 FC 18, This AM TC 14.5 CC 1 FC 13.5, Lost 4.5 ppm overnight. Pool is noticeably clearer today, the sediment that was stired up with brushing last night was the least amount yet. Its getting close to being finally cleaned up. I added 1 gals this am after I took the sample to keep the FC high during the day hopefully it helps.

Sounds like you are making progress. Try to keep your FC between 10 and 15 unless you are less worried about liner bleaching (I have a 10 year-old liner so bleaching isn't an issue to me--and it's hard to tell what is from my few "shocking times" that exceeded the Best Guess Chart's numbers....and what is from 10 years in the sun.

[TomDehoff]

Back with today's numbers. Added 3 gals had TC 18.5 CC 1 FC 17.5 after the addition. This AM I had TC 14.5 CC 1 FC 13.5 Loss of 4 PPM overnight. Pool actually is looking good. Brushed again last night and still stiring up sediment in the deep end. Added an additional gal. this am after I pulled the sample in attempt to keep FC high during the day. Wish I could get rid of the CC.

[Watermom]

Wish I could get rid of the CC.
Keep at it, and you will!

[TomDehoff]

Update for today. The pool actually looks almost perfect now. The Chlorine loss overnight was only 1ppm (first time that has happened) Still have CC of 1ppm. Do I continue keeping the TC high till the CC is eliminated? I am assuming its safe to start adding my CYA now too?

[BigDave]

Yep, Maintain shock level for your CC until 1ppm FC loss overnight and > 0.5ppm CC then keep shock level for one more day for good measure.
Sure, go ahead and start adding stabilizer, how do you plan to add? most of us choose to put it in a stocking hung in front of a return.

[Watermom]

I added some to my pool the other day but instead of hanging the sock in front of the return, I laid the sock in the skimmer basket and kept the pump running until it was all dissolved.