Ph and TA out of whack after adding borax

May 13, 2014
35
San Diego, CA
I decided to add borates to my pool today, and started off just fine. I manually chlorinate with 12.5 chlorine. Before I added borax I had TA of 110 and Ph of 7.4. My pool is 10k gallons. First I added 150 oz. Of muriatic acid then 4 boxes of borax. I swept the pool then added another 150 oz of acid and another 4 boxes of borax. Now after several hours I noticed my ph was quite high so I added some more acid, which shouldn't have made as huge of a jump as it did because it pushed it to around 6.8. At this point I decided I should recheck my TA. TA is now at 40. Before I start slingshotting everything back and forth, I figured I would come here and ask first.
 
I decided to add borates to my pool today, and started off just fine. I manually chlorinate with 12.5 chlorine. Before I added borax I had TA of 110 and Ph of 7.4. My pool is 10k gallons. First I added 150 oz. Of muriatic acid then 4 boxes of borax. I swept the pool then added another 150 oz of acid and another 4 boxes of borax. Now after several hours I noticed my ph was quite high so I added some more acid, which shouldn't have made as huge of a jump as it did because it pushed it to around 6.8. At this point I decided I should recheck my TA. TA is now at 40. Before I start slingshotting everything back and forth, I figured I would come here and ask first.

Given the small volume of your pool, I would have broken the acid additions up in many smaller quantities. PoolMath says that adding in 150oz of full strength MA would drastically lower your pH (decrease by 3 units) and take your TA down by 55ppm. That's way too much. You should have added the borax first and then the MA and then in much smaller increments.

The fix now is you need to add baking soda to raise the TA of your water. PoolMath says that 94oz (~5lbs) of baking soda should bring you up to 80ppm from 40ppm. Again though, add it in small batches, maybe 2lbs at a time and test between additions.

To get your pH back up, another 4lbs box of Borax will bring up the pH from 6.8 to 7.5.

You can also use PoolMath to calculate the amount of washing soda to add to increase both pH and TA at the same time.


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If I add more borax, will the borates be to high? I was aiming for 50 ppm on the borates hence the amount of borax added

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If you use PoolMath, you can calculate the effects of adding chemicals. Adding the additional box of borax will increase your borates by 6.5ppm and your TA by 15ppm. So you could add less baking soda and then let the borax do the rest.

Just always be sure to add chemicals in small batches. PoolMath is good at calculating amounts but it's pH calculations lose a little accuracy when you try to make large changes in water parameters.


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I stopped off at Walmart and bought some washing soda and baking soda...
Based off of my ph estimate it recommended adding 43 oz by volume of washing soda. I added 16 and let it sit for a couple hours.
Ph came up to around 7.0 and TA now measures 60.
Pool math recommends adding 29 oz. of washing soda, so I am adding right at 14 oz. now and going to give it some time and measure again.
Is it normal for TA to come up when adding the washing soda? I was expecting to have to adjust ph, then alkalinity, but that doesn't seem like it's going to be the case.
 
It took me nearly a year to learn it even though it's stated right on the pool math calculator that PH and TA adjustments should be made in small increments; partly because there are so many factors about specific pool properties, in specific locations that can make pool reality a little different than just arbitrary math equations.

I got the swinging PH/TA going a couple of times trying to minimize the number of PH down adjustments I was having to make. Instead of adjusting PH down about .2 with about 7-8 oz's of MA at a time, I thought I'd get ahead of it and put in 16 oz's at one time and move it from 7.9 to 7.2 (or something like that) in one whack. But for me, it didn't seem to work like that. It did do what I wanted PH wise, but for only a day or two, but it really, really dropped the TA; and then the PH was back up to the top of the range in about the same amount of time anyway. So in my case, it caused me to use more product trying to do less work, because I ended up using more MA and baking soda than if I had just stuck with the small adjustments, and it didn't minimize the frequency for making PH drop adjustments, because the pool just seemed to shoot right back up to 7.9 in a short amount of time.
 
I slowly crept up on everything, and think I have it dialed in... I'm sitting at 5 TC, .5 CC, 100 TA, 7.5 Ph, 40 CYA, and sitting at 400 calcium hardness.
Thanks for all the assistance!

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So with those numbers, your CSI is +0.14 which is balanced but on the positive side. If your pH drifts up to 7.8, then your CSI will be +0.4 which puts you into the "possibility for scaling" zone.

If you let your TA come down to 70ppm, then your CSI will always be below 0.2 for a pH between 7.5-7.8. So keep an eye on your TA and let it come down if it does so in its own. There's no reason to keep it at 100ppm if it wants to drift lower. With the 50ppm borates, you'll have plenty of buffering capacity at a TA of 70ppm.


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