What to adjust first?

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Nasantos

Nasantos

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LifeTime Supporter
Jun 1, 2015
18
Crown Point, IN
Here are my test results:
FC 8.5
CC .5
PH 7.2
TA 180
CH 350
CYA 55

Pool calculator says 108 oz of soda ash and also to lower alkalinity to adjust ph down to 7-7.2 with acid. Should I get the ph up first and then add acid to get the TA down? Aeration is not a good option for me I have no fence and a auto cover so it's always got to be shut unless we are in it.


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Soda ash will raise TA as well as pH. I wouldn't mess with anything right now. Your pH will rise because of your TA, so check that daily and add acid as needed and your TA will go down over time.

Hop in!
 
So wait for ph to come up and then add some acid to start getting TA down? If u don't mind answering a question for me to help my understanding of general pool care, if I wanted to achieve perfect pool Chems without waiting for ph to come up what would be the process for adjusting those values?


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You accelerate pH rising (with no change in TA) by aeration. It drives carbon dioxide out of the water.

If you wanted to accelerate lowering the TA, you do that through a combination of aeration and acid addition while keeping the pH low as described in Lowering Total Alkalinity. However, these are somewhat more advanced procedures and your higher TA is apparently not causing much of a pH rise which is why everyone is saying not to worry about it at this point.
 
I was on vacation for the last week and came home to no changes in my pool Chems other than the chlorine was high. I have a auto cover and it's closed 24/7 when not in use. I left it open 12 hrs today with 2 roman fountains and our slide going to attempt to aerate the pool and raise the ph. It looks like it went up a little, maybe .1, from 7.2 to 7.3. Does that seem like a normal rise in ph using aeration?


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After a couple days of heavy use my PH rose up to 7.6 and I thought this would be a good time to add some acid in a attempt to get the TA lower I am thinking that a eventual goal of 100 iwoukd be good. The TA was already down on its own to 160 from 180 a week ago and after adding 2 gallons of acid the ph dropped down to 7.2 and TA dropped down to 150. I was expecting the TA to come down further and I'm wondering if it's not reacting correctly because I don't think my TA was as low as it was supposed to be when I added my borax to achieve 50ppm level. I added my borax before I started doing my own testing back when I was following the direction of my pool store who was also my pool builder. I worked with the pool store for a few weeks after opening my pool this year and we had gotten the TA down to 180 from around 400 when they instructed me to add the borates. I'm wondering if this could be why I'm having difficulty getting my TA down? And if I'll be fighting this forever or is their something I can do?

Thanks in advance for any advise!

I know I'm probably meddling too much right now but I'm excited about learning as much as possible and experimenting with my new toy


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The drop in TA is solely a function of the amount of acid added. The Borates don't change that relationship. What the Borates change is that it takes more acid to lower the pH and likewise more carbon dioxide outgassing to raise the pH (so the rate of rise is slower).

2 gallons of full-strength Muriatic Acid in 28,000 gallons will lower the TA by 36 ppm. So you are right that it is strange for the TA to only go from 160 to 150. Is it possible that there was some static electricity on the dropper tip during your last TA reading? Or perhaps it's the 160 reading that is wrong because you said that "the TA was already down on its own", but that doesn't happen without acid addition. That probably makes more sense because the drop from 180 to 150 is roughly what was expected.
 

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Thanks! That does make more sense, several of my recent tests were around 180 so I probably had a incorrect reading. Do you think I should continue to try to bring the TA down to the 100 level? I was thinking a gradual progression of adding a couple gallons of acid every time my ph comes back up on its own. Do you think this is a good strategy?


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Nasantos said:
Thanks! That does make more sense, several of my recent tests were around 180 so I probably had a incorrect reading. Do you think I should continue to try to bring the TA down to the 100 level? I was thinking a gradual progression of adding a couple gallons of acid every time my ph comes back up on its own. Do you think this is a good strategy?


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Click to expand...
I think it would be better to let poolmath determine how much acid you need to bring pH back down to 7.2 every time it rises to 7.8. It may end up being gallons, but it would be a calculated dose, not a massive chemical dump. Here's what can happen when pH gets too low and why you don't want to drive it way down. Even if it's not this extreme, it will happen on a small scale.
Maintain your chemicals correctly
 
I am in the slow but steady process of lowering my alkalinity. I have been using pool math to determine how much acid to lower my pH from 7.8 range down to the 7.0 range and then I've been aerating to bring PH back up. This process brings my alkalinity down about 10 ppm every time I add the acid. I'm wondering what is a good target alkalinity to shoot for? I am seeing ranges for vinyl pool is listed as 70-90+ and I'm not sure what the 90+ means?


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TA is a very subjective target level. 70-90+ means that most people keep their TA above 70 and somewhere near 90. 70 TA allows your pool to have some buffering capacity against pH changes that it would not have if it were too low. The general rule is, the higher your TA, the faster your pH will rise with aeration. So the recommended range is there, but if your pool has very little pH rise at 100 ppm TA, don't worry about lowering it on purpose. Just monitor your pH and keep it between 7.4 and 7.8 and only lower it when your pH goes ABOVE 7.8. Let your pH be "happy" at whatever TA gives you low pH rise, hence, lower acid usage.

EDIT: For instance, my TA has been at 100 to 110 most of the season so far and I've added 30 ounces of acid total this year (two additions since April). pH always between 7.4 and 7.8.
 
What it means is that if your pH is holding steady and your TA is 110, just target 110 and forget about it. If you're below 70, you can target somewhere around 80 so it will tell you how much baking soda to add. Every pool is somewhat different, and TA is the least important parameter. Wherever your pH stabilizes, that's the sweet spot and you should just leave it alone.
 
I think I got it! Thanks for the help! I feel like it's pretty stabile. The ph slowly rises and that's only when I leave the cover open and run the fountains and slide all day or we use it a lot, which is almost all day every day lately. I feel like it would stay at 7.8ph if I didn't lower it with acid. Should I experiment with how long it would stay at 7.8 before going up to 8.0 before adding any more acid? I couldn't be happier with my pool all around since tfp. I have been buying 12.5 bleach at Menards for $1.96/gallon and I am amazed at how easy and inexpensive this has been.


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