PH going up again!

[Watermom]

I don't think your alk went up with the addition of muriatic acid. Yes, if you add more acid, the pH will go down further. What is your pH and TA now?

[Mr.Mooks]

On Friday my PH was 7.9 and Alk was 167 ppm then I added 1/2 gallon of Muratic and 1/2 Gallon of liquid CYA got another test Saturday and the PH is 7.4 and Alk was 176.

[aylad]

My guess would be faulty testing....but you could verify that by testing same sample from two different stores.....

Janet

[Mr.Mooks]

That is likely. I have put in the CYA in a sock so I am waiting for it to dissolve. I think I will add 1/2 gallon of Muratic tommorow and then I wait a few days and get another test. All I am realy trying to acomplish is to lower the runtime and percentage on my SWCG so it will last a few years. Everyones help on this site has been awesome. Thanks to all. After next test I will post results and proceed with the suggestions I receive here.

[waterbear]

It is definitely testing error (or more likely, the normal variance from the precision of the test.) You numbers look like their are either from a strip reader or colorimeter. If they are from a strip readier they are just not to be trusted. If they are from a colorimeter such as the LmMotte Waterlink system they are in spec because, if my memory serves me correctly, the LaMotte UDV TA test has a precision of +10 ppm / - 20 ppm for a variance of 30 ppm. (The Taylor titration test, which does not use any fancy meters is actually ore precise with a precision of +/- 10 ppm!)

[Mr.Mooks]

Thanks Waterbear. Not sure what the test is but no strips are used. My water sample goes into about 6 if not more little clear vials with couloured lids on them. Then they are put 1 at a time into a little red box connected to a computer. After a few minutes they give me printed results. If I can get through this season this way I will purchase a taylor kit throughout the winter. With all the install and setup costs with the pool cash is tight. Thanks everyone for all your help. I will post test results ina few days after CYA have dissolved. Then again I will call on your guideance.

[waterbear]

Thanks Waterbear. Not sure what the test is but no strips are used. My water sample goes into about 6 if not more little clear vials with couloured lids on them. Then they are put 1 at a time into a little red box connected to a computer. After a few minutes they give me printed results.

Sounds like a LaMotte Waterlink Express. I know it well and am certified on it by LaMotte. It's good for pool stores since a whole batter of tests is done in 3 minutes BUT it does not have the precision of the Taylor kit and the type of variance you see in test results is common.

Bad new is the CYA and Calcium Hardness tests with this unit are even worse than the TA test with both of these being +10/-25 ppm! (This is a variance of 35 ppm which, for a CYA test is VERY significant!)