Help with adding dry acid to small vinyl pool high PH!?!

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
momofautisticchild
Pool Newbie
Pool Newbie
Posts: 4
Joined: Tue 01 May, 2007 17:20

Help with adding dry acid to small vinyl pool high PH!?!

Postby momofautisticchild » Fri 11 May, 2007 08:27

hello,
I went to the pool store to have my water tested. I have a vinyl above ground pool that is 12ftx3ft (1779 gal) my readings were as follows:

free chlorine 2.9ppm
total chlorine 2.9ppm
combined chlorine 0.0ppm
PH 7.9
Hardiness 140ppm
Alkalinity 190ppm
Cyanaric acid 30ppm

I was told by the pool store to add 16oz (2cups) of dry acid to bring down the PH. I just wanted to make sure that sounds correct, I did shock the pool last week pretty high (around sunday) and as a result I havent had to add any chlorine (due to cyanaric acid added on sunday?) I just wanted to make sure they werent getting "false readings" for the PH because of the high chlorine or what not. Im fairly new to this pool ownership (second summer) and havent had this problem with having to add these chemicals. They also told me it is rare that a small vinyl pool needs dry acid. I just wanted to check with you guys before I do what the pool shop recommends so I dont ruin the water and have to drain or what not (BTW the pool water has been crystal clear, no smells and no algae at all) so would it be safe without adding the dry acid??

thank you!!


pool_tech

Re: Help with adding dry acid to small vinyl pool high PH!?!

Postby pool_tech » Fri 11 May, 2007 13:47

Yes with an alkalinity of 190 you may find the pH wants to climb up a bit. Are you sure of the quantity though? 16 oz seems a bit much. To drop your pH to 7.5 you'd need about 150 grams. I say add 150 grams and retest.

A high alcalinity reading combined with high pH *may* cause cloudy water.
momofautisticchild
Pool Newbie
Pool Newbie
Posts: 4
Joined: Tue 01 May, 2007 17:20

Water is clear but dry acid amount does sound too high

Postby momofautisticchild » Fri 11 May, 2007 16:29

Hi there,
my pool water is crystal clear and has been which is interesting. It has been holding on the the chlorine (Chlor-save was added last weekend)
I did call the pool shop to confirm about the dry acid, I was concerned because on the bottle it said 2 1/2 cups per 10,000 gal. Then they told me to add 8oz. and then finally to add 4oz. Im pretty hesitant because Im worried about adding to much (did that with water clarifier last summer and ruined the pool water by trying to correct)

Thanks again!

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