0 Alkalinity

[chessie6]

Hi, I'm helping some friends balance their ig pool after opening for the first time - it came with the home they bought late last fall and of course they opened to a nice bright green lime jello water. Their PH is extremely low (the test results in the vial are yellow, not even orange :? ). Then in testing the alkalinity, the water sample doesn't even turn green when adding #8 - it turns pink. They've been gradually adding borax and even after adding an entire box the test results for the PH haven't changed.

My question is this: should we start adjusting the alkalinity first with baking soda or should we continue adding borax and then adjust the alkalinity?

Further info - the pool guy had added 5 gallons of liquid shock which did basically nothing. Yesterday we drained and replaced about 1/2 the water to bring down the cya from 120 to 60, added 4 gallons of 12.5% and today the pool is a lovely blue and we can even see the bottom drains in the 8' deep end! TFP rocks and they are so grateful I've introduced them to you!!

Thank you so much for your help,
Jan

 

[jblizzle]

Yes. Raise the TA with baking soda to at least 70 ppm or so and then dial in they pH.

Remember that the pH test is inaccurate when FC greater than 10ppm.

 

[JasonLion]

I would do borax to adjust the PH first. If you start with baking soda things will go more quickly, but you will end up with a very high TA.

 

[jblizzle]

Hmm ... I thought you wanted to get some TA first ... maybe 40ppm or so of TA first and then raise the pH would be better?

 

[JasonLion]

If TA starts low, but above 0, raising TA part of the way first makes the process go faster and more predictably. But if you do that when TA starts at zero, the TA will end up way too high.

 

[jblizzle]

Thanks for the clarification. File this in the memory banks

 

[chessie6]

I thought too that getting some TA would make sense .. tomorrow morning we'll find out if the chlorine is holding overnight yet or not, bringing us closer to the goal of a 7 ppm FC maintenance reading. I do want to be careful not to raise the TA too high or else if their pool is like mine, they'll have to keep adding PH- every week or so when the bleach brings it up. My PH stays balanced more easily when the TA is lower. So we'll continue adding borax . . Thanks much!

 

[chem geek]

Or you can use pH Up (Arm & Hammer Super Washing Soda -- careful: NOT the detergent -- ingredient is Sodium Carbonate) which will raise both the pH and TA and won't overshoot the TA if you stop when the pH gets into the 7's.

 

[chessie6]

Washing soda - that sounds great. Thank you again!

 

[chem geek]

You'll need baking soda as well since the washing soda won't get the TA all the way up. The minimum amount you'll likely need if the pH is 4.5 and not actually lower (the TA test turns red at pH 4.5) will be 3-1/2 cups of washing soda per 10,000 gallons and 13-18 cups of baking soda if all the carbonates were driven out of the pool. If only half the carbonates got removed (via outgassing), then you'd need around 17 cups of washing soda and no baking soda. Your pool will likely be somewhere in between these, probably closer to the former than the latter. So just carefully add the washing soda and monitor the pH and stop when you get the pH into the low 7's (7.0 to 7.2 or so). If you overshoot, don't worry since you can touch that up later. After your pH is up even if it got too high, you can adjust your TA and finish touching up the pH at the end if needed.

 

[chessie6]

I'll send him the info - thank you. We are having issues figuring out the gallonage since the pool is a freeform lagoon style - it has an approx 3 1/2 foot shallow section and then a slope to an 8 feet deep end. I know you have info here on calculating it - just haven't gotten there yet and I'm recommending approximate dosages/testing/adjusting for now. I go by my pool dosages of 24,000 gallons and in figuring their pool has less . . and recommend accordingly. This morning's results are that they lost only 1 ppm chlorine overnight!

 

[chessie6]

They are very grateful - or should I say VERY VERY grateful - for the info here and are planning to register and join our community!