Can't Raise Chlorine Level After (2x) Stain Treatment

[Chuck_Davis]

Re: Water turning green after liquid chorine added

New player, same game, so I thought I'd append my situation and questions here.

14,000 gallon inground pool with 2 year old epoxy surface, zeolite filter. Minor metal staining, probably due to some galvanic corrosion. (Working this issue on a separate thread.) Highest metal reading in early spring, with little/no sequestrant added over the winter, was 0.4 ppm copper. (We don't close the pool.)

Performed standard ascorbic acid (AA) stain treatment. (BTW - 2.2 lbs. of pure ascorbic acid is $17-$18 on eBay.)

Tried to keep ahead of algae before/during/after the AA treatment with Polyquat 60. (There was an algae breakout while the chlorine levels were dropping prior to the AA treatment. Knocked it back with Polyquat 60 and vacuumed the dead critters to waste.)

After the AA treatment added Metal Trap sequestrant. Also used Metal Trap 2-part flocculant, which is supposed to physically precipitate the metals that were lifted by the AA. It took the predicted 4-5 days for the flocculant to clear, after which I vacuumed to waste.

The water was still cloudy, so I assumed that the algae had broken through somehow. (I hadn't seen this thread before, where it is noted that sequestrant can turn the water cloudy.)

Raised pH and TA and then started raising the chlorine using liquid chlorine. As soon as I got measurable chlorine levels I saw that I had 1-2 ppm combined chlorine, which seemed to confirm the algae.

5-6 days after the AA treatment I took a chance, put in 2 cups of trichlor and..............instant pea green water.

In for a dime, in for a dollar, I kept adding chlorine - liquid and trichlor - over several days but never was able to reach breakpoint. Could the combined chorine reading be an artifact of the AA treatment? I also dumped in a half gallon of Natural Chemistry Metal Free that I had.

Last evening the chlorine levels were >10 (higher than my LaMotte ColorQ can read). Water was still pea soup green.

This morning the water is now clear and a light blue-green. Can't yet tell if there was any (re)staining of the walls. The PVC fittings are stained, and there is some staining on the wall where a return jet water flow runs parallel to the wall.

Current readings are:
** FCL - 0.67
** TCL - 1.75
** pH - 7.0
** TA - 152 (target is 125-150 per epoxy paint mfr. recommendation)
** CH - 165 (target is 175-225 per epoxy paint mfr. recommendation)
** CYA - 19 (left it low to allow quicker drop in chlorine after shocking / due to high CH did a 1/3 drain/refill of pool before starting AA)
** Cu - 0.0
** Ir - 0.0

Questions:

** Is the combined chlorine reading valid or an artifact of the AA treatment?
** If valid, how can I hit breakpoint without (literally) going back in the soup? (This is the most important question.)
** Does the rapid drop in chlorine from last night reflect anything other than the low CYA?
** Should I take advantage of the low chlorine and low pH to do another AA treatment? There should still be a mess of sequestrant in the water. I also have a CuLator metal adsorbant in the lint basket.

Thanks!

 

[Chuck_Davis]

Earlier I posted about doing an ascorbic acid stain treatment, seeing combined chlorine, shocking too early and ending up with pea green water and some re-staining.

I ended up doing a second stain treatment with an ascorbic/citric acid blend. This was a little over a week ago. Algae/floc/mung was vacuumed to waste. It took about a week for the white cloudiness (presumably from the sequestrant) to clear.

The water looks beautiful now, the moreso for just having added borates. I've been using Polyquat 60 to stay ahead of any potential algae. Current readings are:

** FCL - 2.20
** TCL - 2.79
** pH - 7.5
** TA - 151 (target is 125-150 per epoxy paint mfr. recommendation)
** CH - 215 (target is 175-225 per epoxy paint mfr. recommendation)
** CYA - 40

The problem is that I can't get the chlorine anywhere near my target of 5.0. It may spike to 2 or 3 immediately after adding (liquid) chlorine, but then rapidly drops below 1.

I understand that something is consuming the chlorine, but is it still the ascorbic/citric acid from the 2x stain treatment or something biological?

The CYA-Chlorine table shows a shock value of 16, but I'm afraid to do much of any shocking because I might end up with pea green water again. (And I'm getting ready to leave the country for a month, leaving the pool with a house-sitter.)

I'd appreciate any suggestions on how to get the chlorine up to a stable 5 without risking leaving the house-sitter with a messed up pool.

Thanks!

 

[benavidescj]

I am doing the AA treatment right now as well. It will take some time to burn up the AA with chlorine. Give it some time. You will have to anyways because you don't want to shock right after doing an AA treatment.

 

[Butterfly]

Sounds like you are doing the right things . It takes time and must go slow to avoid re-staining, as you know.

My only suggestion at this point is to lower the pH to about 7.2 and keep it there until you are completely done with the process.

Patience, POP, is needed esp when doing the AA treatment and even moreso when the water is colder.