Purple PH?!?!?!?

[Dkoucky]

Fc 5
Cc 0
PH purple
Ta 100
Ch 125
Cya 45

Huge storms this weekend dumped a ton of leaves and debris into my pool. So I immediately added some extra chlorine (3 gallons of bleach) and got the leaves out. The water is a little cloudy now but nothing to really worry about after all the junk that got blown in and the 4.5" of rain, I think it will clear up from the filter and running the robot.

Now my PH is testing purple, could it really be that high? Should I start with 1/2 gallon of muriatic acid? Is it possible there was something wrong with the test? Also my CH is pretty low is that related?

Thanks,
Daniel

 

[JVTrain]

You can get high pH readings when your FC is above 10 but since yours is only 5, I would assume your pH test is correct. Rain can drive pH up in a hurry because rain creates a massive amount of aeration on the pool surface, which increases carbon dioxide outgassing, driving the pH up. Your CH is low and may be a problem for your concrete pool surface so you should address that as well, but get the pH in line first. Use Pool Math to bring the pH down to 7.4 with all of your values input.

 

[Dkoucky]

Thanks! as using the pool math goes purple is way off the scale should I assume it is 8.5 and work from there? Or just keep pouring in slowly and testing until I get a reading that is on the chart?

 

[JVTrain]

Just assume it's 8.2, even thought it's likely over that. Better to go in not far enough in pH than too far. Add dose to go from 8.2 to 7.2 then retest after at least 30 minutes to see where it's at.

 

[JoyfulNoise]

Not to question your methods but are you sure your FC is only 5? You said you dumped in 3 gallons of bleach. What FC does PoolMath tell you that is and how shortly after adding the bleach did you measure pH?

I only ask because the chlorphenol red created from the reaction of phenol red with chlorine is a low pH indicator and anything above 6.0 or so looks purple colored. So I'm wondering if your FC is really as low as you think or if there wasn't enough mixing to get the bleach well mixed.


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[duraleigh]

the colors going from low pH to high pH are....
yellow 6.8 and lower
yellow orange 7.0
orange 7.2
orange red 7.4-7.5
red 7.6-7.8
red violet 8.0
violet 8.2 and higher

 

[Dkoucky]

I added the bleach yesterday after the rain has passed. So it has been at least 18 hours I am fairly confident those chlorine levels are correct. I did not test before dumping the chlorine in so I don't know how much it raised it I just knew that it couldn't have been about 4 and there was a lot of bio matter blown into the water so I knew it would take at least 3 gallons and still keep it in a safe level.

I will see if I can get the pH down tonight and into tomorrow thanks for the help guys

 

[JoyfulNoise]

I added the bleach yesterday after the rain has passed. So it has been at least 18 hours I am fairly confident those chlorine levels are correct. I did not test before dumping the chlorine in so I don't know how much it raised it I just knew that it couldn't have been about 4 and there was a lot of bio matter blown into the water so I knew it would take at least 3 gallons and still keep it in a safe level.

I will see if I can get the pH down tonight and into tomorrow thanks for the help guys

Ok, got it. Good luck in getting the pH down. Hopefully everything gets back to normal really quick.

Cheers.


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[rmturner54]

Interesting bit of info on rain causing aeration. Never thought about it. Thanks.

 

[JVTrain]

A hard rain is one of those events that's PERFECT for driving down your TA if it's on the high range. If you can anticipate it and have high TA (>120 ppm, depending on your situation), lower pH to 7.0 before it happens to reduce TA a decent amount, rain aeration will drive the pH right back up and you can lower pH again, lowering TA again. Rain water itself is actually very low TA so you're filling with nearly zero TA water during the rain. So another way to slightly lower TA. Those millions of little drops can come in handy.

 

[woodyp]

I like your thinking there JVTrain............