Ph high, TA high and green

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

Postby confused » Wed 27 May, 2009 15:10

My ph is over 8 and TA is 144. Is the first step to lower ph with muriatic acid and then aeriate to lower TA until they are in line and then shock the pool for the green algae? When you take off the cover to open the pool what should be the first steps? This is my first year to open the pool and it turned green. Thanks for the help!


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Ph high, TA high and green

Postby chem geek » Wed 27 May, 2009 15:44

I'd lower the pH to around 7.2, but not worry about the TA right now and instead battle the algae by following Defeating Algae . You can deal with lowering the TA later after you've knocked out the algae.
confused
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Ph high, TA high and green

Postby confused » Wed 27 May, 2009 16:18

Does this seem extreme or not? This lady I know that has a 17,000 gal. pool adds 11 gal. of liq. chlorine at the beginning of opening her pool. Does that seem much? I looked on the pool calculater and for FC at 0 and to raise it to shock level of 11 it says to add 2.2 gal. of 12% bleach (that does not seem like very much) Does this sound like that will be enough to shock it? Or should I use some HTH super sock it with 49% available chlorine. Which to do? I added 2 1/2 bags of shock yesterday and the FC today is 0

FC 0
TC 0
TA 144
PH over 8
CYA 20
Me...
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Ph high, TA high and green

Postby Me... » Wed 27 May, 2009 16:34

I think you should mention how you are getting these readings.
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Ph high, TA high and green

Postby chem geek » Wed 27 May, 2009 18:25

Yup. Specifically, what kind of chlorine test are you using? Is it a DPD test where you compare the intensity of pink/red to a standard? If so, such tests bleach out at high chlorine levels so you could have a very high FC and not know it. If you use an inexpensive OTO chlorine test (the kind that compares against the intensity of yellow), then if it is deep yellow or even orange, then that is high chlorine (orange is very high, red is extremely high) and this kind of test does not bleach out. Or you can use a FAS-DPD chlorine test which can test up to 50 ppm FC as found in the Taylor K-2006 or the TF100 from tftestkits.net.

Since your TC is also 0, I suspect that you are bleaching out your chlorine test.
confused
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Ph high, TA high and green

Postby confused » Wed 27 May, 2009 18:53

I bought a Taylor K 2006 this year and tried to test the CYA and it only starts at 30 and mine was less so it did not read. They need to make those test go to 20 ppm on CYA! I wanted to know what it was so our local ACE Hardware store tests pool samples so I took it there. We have dumped in 1 gal. of muriatic acid and the ph is still at least 8.
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Ph high, TA high and green

Postby chem geek » Wed 27 May, 2009 22:54

OK, so I'm a little confused. The Taylor K-2006 has you measure Free Chlorine (FC) and then Combined Chlorine (CC). You reported Total Chlorine (TC) so did you add these two together rather than just report CC separately? When you added the DPD powder to the sample, did you not see any flash of pink and add more powder to see if there really was any chlorine in the water?

Was the pH measured high before the chlorine was added? If so, then you can add more acid to lower the pH. Did you do an acid demand test in the Taylor K-2006 to see how much acid it said you needed to add?

As for the CYA test, you can get one that measures down to 20 ppm here from tftestkits.net and it's based on the Taylor K-1720 except that's it less expensive.

If her pool is exposed to direct sunlight, then your CYA is low. Was her CYA higher when she closed the pool in the winter and is she opening the pool now for this season? If the CYA dropped, then I suspect that the pool was "let go" (i.e. to zero chlorine) and bacteria have converted some of the CYA into ammonia. You can get an inexpensive ammonia test kit from a pet/fish/aquarium store if you want to see if that's what is going on. In any event, you can do a bucket test to see how much chlorine it will take before it starts to hold. 1/4 teaspoon of 6% bleach in 2 gallons is 10 ppm FC. It can take an extraordinary amount of chlorine before the FC starts to hold since every 10 ppm CYA converts to 3 ppm ammonia that takes 25 ppm FC or so to clear -- in the worst case -- some ammonia can outgas or otherwise dissipate (get consumed by algae and filtered out).

Richard
confused
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Ph high, TA high and green

Postby confused » Thu 28 May, 2009 15:25

I am sorry. That is my fault. I meant to type CC not TC. When you say a pool is let go during the winter I get a little confused. I was not aware that you did anything in the winter to your pool. Are you supposed to do something to it? We live in Indiana. Maybe I should find out how you close your pool and what you do to open it. Just wondering how you do yours. sorry for the confusion. Thanks :)
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Ph high, TA high and green

Postby chem geek » Thu 28 May, 2009 18:06

If the pool doesn't freeze over, then you should continue to chlorinate your pool, adding some bleach or chlorinating liquid every now and then. When the water gets colder, below 60F or so, you should find that you can add chlorine less than once a week -- even 2 or more weeks -- as it will hold rather well (especially if the pool is covered).

If you live in a climate where the pool freezes over (or the pipes would freeze), then you should wait to close the pool as late a possible so that the water temperature is as cold as possible (though 50F is fine), then shock with chlorine, then add PolyQuat 60 (plus other closing items as described here for above-ground and here for in-ground. Even more important is that you open up the pool as soon as the water is thawed (see here ) and starting to warm up, but is still cold (i.e. 50F or so). That way, you can add chlorine before algae or bacteria start to grow to any great extent.
confused
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Ph high, TA high and green

Postby confused » Fri 29 May, 2009 12:39

Thanks! :D

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