OTO Testing Question

[Pappy]

We haven't got the Taylor kit yet, (long story). When I check the chlorine level with the HTH 6 way kit the first drop turns orange, the 2nd drop goes brown, (about the color of fine Kentucky Bourbon) then the color gets lighter with each additional drop. When I'm finished it looks like the FC is about 4. Should I be seeing this?

[Pappy]

Retested with HTH 6 way this evening.
pH 7.4
TA 70
CYA 70

Chlorine was tested straight, 1 part pool water to 1 part distilled water, and 1 part pool water to 2 parts distilled water. All 3 tests showed Chlorine to be about 4. I had my wife, the chemist verify my results.

I'm thinking I have WAY too much chlorine in the pool. I have been adding 3 cups 8.25% bleach each evening because I'm getting a reading of 4 and the "Best Guess" says 5 minimum.

Thanks.

[CarlD]

I'm not the chemist so I am just making a WAG here: Your chlorine level is so high it's finally bleaching the OTO. But I do not know if that is possible. Deep brown with OTO means about 40-50ppm. But after 2 drops? I just don't know.
Now, when you say it reads 4 when you mix 2distilled to one pool, does it read "4" on the scale? Because that means it is "12" (1:1, double the reading, 2:1, triple it and so on) If so, I'd keep increasing the dilution to 3:1 (16), 4:1(20), 5:1 (24), etc. What have you got to lose?

[BigDave]

... first drop turns orange, the 2nd drop goes brown, (about the color of fine Kentucky Bourbon) then the color gets lighter with each additional drop. When I'm finished it looks like the FC is about 4. Should I be seeing this?

No you should not. Don't look at the OTO test until you have all five drops in the the sample. Well, look at it so you can aim but don't read it until all five drops are in.

[Watermom]

OTO is not bleached out even at high chlorine levels. DPD (pink color matching) is. That is probably what Carl was thinking of.

[Pappy]

@ Carl, the scale reading is 4. Which says my Chlorine is 4, 8 and 12 simultaneously? Since I have no way to lower the chlorine levels, other than wait, why waste the reagents with multiple tests. I was just wondering if there's something ELSE going on. Is there something BESIDES astronomical chlorine levels that might cause this? I bought the test kit @ Walmart a month ago, so it should be fresh enough.

[BigDave]

3C of 8.25% bleach should add 3.5 ppm FC to 4500 gallons. If you're only doing this daily, I don't see how the FC could be astronomical. Are you testing FC before or after adding bleach? How many days have you done this? What's the CYA level? Are you still cleaning up the algae?

[Pappy]

CYA is 70. I'm testing about an hour after adding chlorine through the skimmer, pump running, once daily, 2 weeks. I'm not STILL fighting algae, but we had a big problem at opening, about 2weeks ago. Ran through 6 121 oz 8.25% bleach getting water "not green". I've only once seen chlorine test above 5 on the scale.

[BigDave]

Test before you dose to see how low it's gotten. The idea is to be sure you add enough chlorine so it won't be below the minimum before you dose again. Maybe even check mid-day today just to get an idea.

[Pappy]

I'll do that. I'm also going to do the next test 5:1 and see what happens.