PH and TA staying high in SWG pool

[quantase]

We have a three month old gunite pool. We have been balancing the water chemistry very well over the past three months. The PH was at 7.8, we added 7 pounds of baking soda to help with raising the total alkalinity to 90 before starting the salt generator system. Just one week ago we started the salt generator (nature2 fusion- without mineral pack). Now our pH is staying at 7.8 and our total alkalinity is staying at 90 for the past 4 to 5 days. We have been adding the recommended Muriatic acid to try to lower the pH and total alkalinity but it has not decreased at all. We do have an auto cover that we have been leaving uncovered during the day to help get our chlorine to the recommended range since now we are running the salt generator due to our FC had been at 14 (it has been Decreasing over the days to now 8). Any suggestions in lowering the pH and total alkalinity to the ideal measurements? We also have been using the Pool Math app to help guide us. We use Taylor 2005 kit. Our current measurements are as follows:

FC-8
CC-0
pH-7.8
Ca Hardness- 450
CYA- 60

Thanks.

 

[mknauss]

With a new gunite pool your pH will rise and you will need to adjust it with acid regularly for some time. What you are describing is normal.

 

[RMcGirr83]

FYI our pool was finished Nov 2018 and I'm still adjusting the pH weekly. Not as often as when brand new but maybe twice a week now. I doubt if I'll ever not have to adjust the pH.

 

[njones]

Thanks for your responses. I have added muriatic acid twice today. The starting pH was 7.8 so I added 5 cups which Pool Math said should take it to 7.2. Then I retested this afternoon and the pH was 7.6. So this evening I added another 5 cups. I understand it’s fine for the pH to sit at 7.8, but I was just trying to get the total alkalinity down from 90 (or 100 depending on how I read the color change) to 80. It has not budged as of yet. I understand the idea is to add acid to lower the total alkalinity then to aerate to bring the pH back up, but I have not aerated as the pH is rising fairly rapidly on its own. We are new to all of this and appreciate everybody’s help. One follow-up question: I’ve been diluting the acid and either pouring it slowly in the deep end of the pool or occasionally in front of the return jets which are in the shallow end of the pool and next to steps so I wasn’t sure which place was a better place to distribute it. Any thoughts?

This is the spouse of quantase, by the way!

Thanks!

 

[mknauss]

No need to dilute the acid. Just pour slowly directly at the pool return with the pump on. Measure if you must. You do not show a signature so unsure of the volume of your pool. If your pool is big enough that your acid adds are always 32 oz or more then just pour straight out of the jug into the water, slowly.

 

[jblizzle]

There is really not likely a need to lower the pH below 7.8. The lower you go the faster it rises.

May have been better off not raising the TA. Often the sweet spot for a SWG pool has the TA around 60ppm and the pH up around 7.8-8.0 .... assuming the CSI does not get too out of whack.

 

[njones]

Thanks again for the responses. Sorry I’ve been off-line a few days. So just to clarify it is OK to pour the acid in the shallow end where the return jet is?

And raising the total alkalinity was a rookie mistake, I did it just before they converted the pool over to the salt water generator and the values were different for ideal range. I’m using the Taylor service complete test kit and do have a question regarding regarding the total alkalinity test. Do you count the endpoint as when there is no more color change when titrant is added or just when it first turns red? I find the difference is one drop or 10 ppm, so my total alkalinity is either 80 or 90 depending on how I read it.

Today results are as follows.
FC 5.5, CC 0, pH 7.8, TA 80/90.

Not sure if it makes a difference, but we do have an auto cover in the pool is staying covered except for when we swim.

Thanks again for everybody’s help!

 

[jblizzle]

Does that test kit have the FAS_DPD chlorine test (uses powder)?

All tests are done by counting drops until the last drop causes no further color change, and not including that last drop in your total.

 

[njones]

Yes, it does. In that case, the TA is 90....

 

[RMcGirr83]

You don't count the last drop if it no longer changes the color.