Oops - I wonder what my pH is?

[Poolnerdgrandma]

So, I added CYA (7-8 pounds) and that is now looking good (70). I also started running the pool 24/7 to heat it up. I also got a migraine (my excuse for what happened next).
I got all my shiny new reagents from TFTests, and did a full suite of tests. Chlorine through the roof! 22. (it's still only February , and I hadn't adjusted the swg down to account for the additional runtime.)
Quickly turned off the swg, so that number will drop fast. pH purple.. what? I had figured the CYA would have dropped it! No worries, add some MA. THIS is where I'm blaming the headache. Obviously the pH was reading high because of the high chlorine level.
This morning FC is 20, pH LOOKS like 7.2-7.4, which would make me super happy. IF I COULD TRUST THE TEST.
Kids are coming over. Should I add some baking soda blindly so the pool doesn't burn their skin?
Are the other acid/base tests accurate if FC is high? I can run those.
Pool is 88 and it's a beautiful day. How do we go swimming?

 

[mknauss]

What is the TA?

 

[Newdude]

Pool is 88 and it's a beautiful day. How do we go swimming?

You hop in, with a warm and fuzzy feeling that your FC is between min and SLAM.

If the PH is not in the 7s, you may get a little eye irration that won't be a deal breaker. Besides, it's not like you're the grandkids diving around with their eyes open for hours. Goggle up if you're swimming laps and it won't even be an issue.

Then, when the FC falls below 10, adjust the PH from the reliable reading if necessary.

 

[Poolnerdgrandma]

What is the TA?

130

 

[Poolnerdgrandma]

You hop in, with a warm and fuzzy feeling that your FC is between min and SLAM.

If the PH is not in the 7s, you may get a little eye irration that won't be a deal breaker. Besides, it's not like you're the grandkids diving around with their eyes open for hours. Goggle up if you're swimming laps and it won't even be an issue.

Then, when the FC falls below 10, adjust the PH from the reliable reading if necessary like.

We just bought goggles for the two younger littles. 4 year old lives in them. (Speedo Sunny G, if anyone is looking for REALLY GREAT kids' goggles). I'll pop those on the girls (who live to emulate the big guy) and we should be fine.

 

[mknauss]

130

your pH is well into the 7's.

 

[Poolnerdgrandma]

your pH is well into the 7's.

Well, with 3 littles in the pool, sunny day, and warm water, the FC will drop pretty fast, and I'll be able to test the pH.

 

[mgtfp]

The reason why the pH-indicator doesn't work at high pH is that phenol red changes into chlorophenol red. The colours look similar, but the change from yellow to red occurs at lower pH:



At normal pool pH in the sevens, chlorophenol red looks red, hence it usually looks like it tests high at FC above 10. But when pH at high FC looks like low to mid 7s, then it might actually be below 6. But with a TA of 130, it should shoot up pretty quickly from those low levels.

What you can do to confirm that you are out of the "danger zone" is the diluted test. Take a pool sample and make a 50:50 dilution with distilled or deionized water and mix well. Then make a pH test with this diluted sample.

This only works with distilled or deionized water, not with tap water, for two reasons:

1) Distilled water contains no chlorine, so this dilution will half the FC-level, FC 20 will turn into FC 10, where the pH test works.

2) Distilled water has very low alkalinity. But you pool water has alkalinity and is therefore buffered. When adding distilled water to the pool water sample, it will buffer pH-changes due to potential pH-differences of the distilled water. This of course only works to a certain degree. A 50:50 dilution should work.

This should give you some peace of mind that you pH is by now back in save waters.

 

[an1vrsy]

For the few times my FC is over 10 ppm, I use the Apera PH60 (the anchor link takes you to Amazon for pricing) when testing pH. Now I am not a chemist that can explain if the digital tester is fool proof above FC 10 ppm but others will have to chime in on that.

 

[mgtfp]

For the few times my FC is over 10 ppm, I use the Apera PH60 (the anchor link takes you to Amazon for pricing) when testing pH. Now I am not a chemist that can explain if the digital tester is fool proof above FC 10 ppm but others will have to chime in on that.

I'm not a chemist either. But a pH-meter definitely works above FC 10. The reason why the drop test doesn't work, I have explained in my above post. And this obviously doesn't apply for an electronic meter.

 

[Poolnerdgrandma]

I think we just solved the problem of too-high chlorine. First poopisode in 4 years of pool ownership.
FC was already high (14). I dumped in a gallon of FC and turned on superchlorinate. When is it safe to swim again (pool is closed for the day, just wondering about later in the week)?

 

[Newdude]

Swimming is safe between min and SLAM. If the poop was nuclear with bacteria, you'd have no FC left. If you have FC left, it's sterile.

Now. That's not to say that being sterile won't still gross you out, so hold the half SLAM for a day just to feel better about it.

poopisode

We always went with 'code brown'