High pH, Good Alkalinity

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
Tom1090

High pH, Good Alkalinity

Postby Tom1090 » Wed 20 Aug, 2008 07:44

We returned from vacation to a dark green pool. We gave it a couple of heavy shocks, and all the green went away, but now it is cloudy, and the filters will not clear it, even after adding, Ultra-Brite Enhancer (from Leslies) three times. We live in Raleigh NC, and it has been very hot here the last couple of weeks.
I just raised the alkalinity yesterday from 50 ppm to 100 ppm.
Free Chlorine was 9 yesterday, so pretty high, but this will go down shortly.
Our alkalinity is 100 ppm, and our pH is above 8.0. 0ur pool is 40,000 litres. So I need to get the pH down, without disrupting the alkalinity.

Cyanauric acid is about zero right now.

I just added two pounds of sodium bisulfite (left the filters running the whole time...seems to be mixed reports whether it is best to leave the system circulating or not....This was about 1 hr ago.

What next?


chem geek
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Postby chem geek » Wed 20 Aug, 2008 10:39

You'll need some CYA in the water or else the chlorine will breakdown too quickly from sunlight. As for clearing the cloudiness, you can have pool owner patience as maintaining shock levels of chlorine will eventually clear it (assuming circulation is decent) or you can spend some more money and get OMNI Liquid Floc Plus and then vacuum to waste what settles to the bottom (assuming your system can do that). Regular brushing and also cleaning the filter if the pressure rises helps.
Tom1090

pH 7.4, Alkalinity 100 PPM, Chlorine Zero, AND Cloudy

Postby Tom1090 » Thu 21 Aug, 2008 19:21

OK, so now I have the pH (7.4) and TA (100ppm) in a near perfect balance. The chlorine is near zero, but I can fix this quickly if necessary.
My Calcium levels are very high (450-500 ppm)....could this be what it creating the cloudiness?
I added CYA and phosporus remover yesterday, so now CYA is 15 ppm, and the phosphate should be well down from its previous high of 300 ppb.
I still need to add another 1.25 ppm of CYA, but would like to clear up the cloudiness issue first, just in case I need to get rid of some water.

Any ideas?
chem geek
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Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
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Postby chem geek » Thu 21 Aug, 2008 20:35

Yes, high levels of Calcium Hardness combines with a higher pH or higher Total Alkalinity can make the water cloudy. However, you had algae and killing algae has it turn cloudy and that takes time to clear. If the cloudiness were simply due to the high CH, then lowering the pH would clear it, but your numbers would not lead to excessive cloudiness until your pH got much higher.

See this link for what a pool getting cleared of green algae looks like and note that it goes through a cloudy stage before becoming clear.
Tom1090

Still Cloudy

Postby Tom1090 » Fri 22 Aug, 2008 19:15

Great pics. Our pool looked pretty much like than, and we definitely did the shock treatment, but it has been a week now and we just can't get past the cloudiness. I just shocked it again, so we will see what it looks like tomorros... :(
chem geek
Pool Industry Leader
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Postby chem geek » Fri 22 Aug, 2008 20:25

So if you have a way to vacuum to waste, then you can use OMNI Liquid Floc Plus to accelerate the clearing (just follow its instructions adding the floc, turning off the pump, waiting, vacuuming to waste). This is especially useful in a pool with no floor drain as circulation is poor near the bottom.

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