Still slamming - question about pH/TAC

[survivalcar]

I think my CYA is 60 but honestly I keep looking at it and it's so sensitive that I'm not sure and it may be closer to 70. I know the strips are inaccurate but just for comparison, the CYA on the strips is definitely between 30-50. So having two sources, one I can't really tell and the other I can't really trust, I figure my CYA is 60. Because of my uncertainty, last night I threw an extra gallon of chlorine in. First test this morning, FC was 26, and now, after a lot of afternoon sun (4:45 pm EST), it's back to 24. The water is pretty clear, I think as clear as it gets.

I was thinking tonight I'll do the OCLT, but in the meantime the pH has crept up to 7.8, and I'm not so sure about the TAC*. Should I adjust the pH or TAC in the pool before doing the OCLT? Will that affect the test? And if not, when should I start to worry about those things?

*Re: the TAC measurement, at around 11 drops (110 ppm) the water turns from green to pinkish but then clear, and about after 5 seconds, turns a little greenish again. It doesn't stay pink until 14 drops (140 ppm). Which is the correct measurement? Just for comparison, on the strips the TAC looks around 100.

Thanks for your help, this resource is amazing

Chris

Hardness <50
FC 24
CC somewhere between 0 and 0.5
pH 7.8
TAC 140?
CYA 60?

 

[triptyx]

The pH test is not useful when FC is above 10 - it reads wrong so we generally ignore it.

While slamming, the only thing you need concern yourself with is the FC number.

With regards to the TA test (ignore it until you're done SLAMing), the test is complete once the water goes hot pink and stays hot pink, and doesn't get any more hot pink when you add a final drop (which you do not count towards your results). You'll get a swirl or three to pinkish and then back to green while still adding drops, and often a medium pink when you're one drop away from your total.

 

[Richard320]

The pH test will be inaccurate with FC above 10. So ignore it for now.

The TA sounds like 140. Maybe 150. You keep adding drops until the color gets a brilliant Barbie Pink and the last drop doesn't change anything and deduct it. So at 11 it shifts to grey, at 14 it goes pink,. maybe at 15 it goes Barbie Pink, but 16 doesn't do anything. You deduct 16, so TA is 150.

Check it again when FC is below 10 and you can test and adjust the pH.

Let us hope the OCLT passes.

 

[mknauss]

Your pH test is invalid at FC greater than 10 ppm.

Do not be concerned with TA. That is the last item to adjust. If necessary.

Take care.

 

[ajw22]

PH is unreliable with FC that high. Ignore the PH until FC is below 10.

Do the OCLT and see where you stand

 

[survivalcar]

Thanks so much. I would have guessed the opposite about the TAC.

 

[survivalcar]

The OCLT didn't pass, which leads me to believe that I've been misinterpreting to CYA reading. I've been brushing, vacuuming, backwashing, rinsing and maintaining the FC at 24 for two weeks and it's still a little bit cloudy. Does it seem like the most likely explanation is that my CYA reading is incorrect? Is there any harm in treating it like the CYA is 70, and thus maintaining the FC at 28? How long should this whole process take? I'm going to run out of chlorine and the FC testing agent again!

Thanks, you guys are incredibly helpful.

Chris

 

[mknauss]

You could, but I doubt it is necessary. You have a big pool. With a sand filter. The process is slow with those facts.

Have you used DE in your sand filter yet?

 

[survivalcar]

No, I didn't know that was an option. I thought filters were one or the other. Do you mean I can just empty that big tank and fill it up with something else?

Thanks

Chris

 

[mknauss]

No! Read this Pool School - Add DE to a Sand Filter