High TA Low PH and No Free Clorine reading

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
pbecker09

High TA Low PH and No Free Clorine reading

Postby pbecker09 » Wed 10 Jun, 2009 07:48

Since I opened my pool 6 weeks ago my PH is 6.2 my TA is 230 and I have no free chlorine reading. I have a SWG. I have used muratic acid and got the reading to 120 and then started to raise the PH and everytime it also raises the TA back to 230. My stabilizer is ok. I just started to shock the pool thinking I need to get rid of my chlorine lock then work on the other issues and have shocked 2 nights in a row and still no chlorine reading. I need to know which issue needs to be addressed first. I have dumped a lot of chemicals and money in this 20000 gallon inground vinyl lined pool and do not know what to work on first.


chem geek
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High TA Low PH and No Free Clorine reading

Postby chem geek » Wed 10 Jun, 2009 10:20

To raise the pH without raising the TA you aerate the water. You never add any chemical to raise the pH when you are trying to lower the TA. The procedure for lowering the TA is described in this post.

Is your SWG generating chlorine? Did you check your salt level? Have you cleaned your SWG cell? Do you have Cyanuric Acid (CYA) in the pool? If you don't have any CYA, then any chlorine you add will get broken down by sunlight quickly (lose half of the FC every 35 minutes in direct noontime sun). If you are losing chlorine overnight, then it's not a CYA issue (or not only a CYA issue).

Was the pool "let go" over the winter and got to zero chlorine? If so, then bacteria may have converted some of the CYA to ammonia. Again, check the CYA level and you can also get an inexpensive ammonia test kit from a pet/fish/aquarium store. If you've got ammonia in the water, then it can take a LOT of chlorine to get rid of it. You can do a bucket test to estimate how much chlorine it will take -- 1/4 teaspoon of 6% bleach in 2 gallons is about 10 ppm.
pbecker09

High TA Low PH and No Free Clorine reading

Postby pbecker09 » Wed 10 Jun, 2009 13:49

I did have the CYA checked and it is good. I did not add anything to increase the PH until I had the Alkalinity down to 90 with Muratic Acid.I did this 3 times. Once I saw the alkalinity was down I worked on the Ph as soon as I did that the Alkalinity would raise to above 200. All the time I did this I had no free chlorine reading. Can this be a chlorine lock. I do live in Ohio and we close the pool in September and open in May. I also have left it uncovered for the past week and pointed the jets up to increase the PH.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

High TA Low PH and No Free Clorine reading

Postby chem geek » Thu 11 Jun, 2009 00:07

If you measure ammonia or Combined Chlorine (CC) in the pool or if the CYA dropped over the winter, then it's possible your pool will have a very large chlorine demand. You can just keep adding chlorine until it holds or you can do a bucket test with pool water seeing how much chlorine it will take before it starts to hold. 1/4 teaspoon of 6% bleach in 2 gallons is 10 ppm Free Chlorine (FC).

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