There is nothing in the water that can cause the TA to increase.
Something HAS to be added for the TA to go up.
Rapid pH increase with SWCG
- Thread starter flippinGeo
- Start date
Something HAS to be added for the TA to go up.
So no one is adding anything. I'm certain of it. I'm the only one maintaining the pool in this house and I don't have any disgruntled neighbors dumping baking soda in at night. I do have a good bit of visible scaling, and even with just a few year old replaster, a good bit of pitting in the surface... So perhaps that is it? I feel like my hardness is at a good range and I thought by now the plaster should be fully set.
Any thoughts?
UPDATE - I just tested again after adding 100 oz of MA 1.5 hours ago. My target was 7.6 and I'm now down to 7.2? This is crazy. I've confirmed and calibrated my test kit against 2 pool stores and they are all coming in pretty darn close so I don't think its my test kit. I'm also diligent about grabbing my samples from the same location every time and at arm lengths depth.
- May 3, 2014
- 62,689
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Can you add what test kit you are using to your signature? I looked back in some of your other threads and the best I could find was a 'deluxe' test kit. No detail. Many kits will read high pH with a FC over 3 or 5 ppm.
Unless the acid is sitting on the plaster, I don't think that the plaster or scale would dissolve that much, but it's possible.
If it is not the plaster or scale or fill water, then something has to be added if the tests are correct.
Based on the rising pH and TA, the tests are probably correct.
Maybe put out a surveillance camera?
If it is not the plaster or scale or fill water, then something has to be added if the tests are correct.
Based on the rising pH and TA, the tests are probably correct.
Maybe put out a surveillance camera?
Possibly defective plaster dissolving.
When you were on trichlor, the acid from the tabs would hide any pH and TA rise from plaster dissolving.
When you brush the pool, do you see a white cloud?
When you vacuum, do you get a lot of plaster granules coming up?
So when brushing I definitely do see clouding around the brush head. Full disclosure, I don't brush as much as I should. I can't say I see granules from vacuuming.
That might be it, but the plaster would have to be really weak to dissolve that much.
You would be losing about 1 lb of plaster per day, which would be over 1,000 lbs. of plaster in three years.
That seems highly unlikely without it being obvious.
The plaster would be really soft and easy to scratch and you would be finding a lot of undissolved aggregate in the pool.
If you are vacuuming a lot, then it might not be noticeable.
The next time you vacuum, use a skimmer sock to catch the debris for examination.
If you get a lot of marble type aggregate sand, put a drop of acid on the granules to see if it bubbles.
How easy is it to scratch the plaster if you use your fingernail or something metal that can scratch?
Last edited:
Thanks @JamesW. I agree that is a lot of plaster. There is a lot of small pitting especially at the stairs, and peppered throughout. This is unfortunate. So assuming, since there is no chemical addition that my plaster is to blame... Is there anything I can do? Certainly it is not in the budget to replaster this thing after only 3 years.
As far as the finger nail test. Generally no, I don't feel it is that soft. However, in the locations where it is pitted, you can run your nail over it and feel granules. I was assuming it was dirt settled in the pitting, but it may be the plaster eating away.
Man this is frustrating. and I'm sure the contractor will claim no fault and it is not likely to end if my favor if I chose to pursue.
I will try the vacuum/sock/acid test this evening when I go to clean it to confirm.
As far as the finger nail test. Generally no, I don't feel it is that soft. However, in the locations where it is pitted, you can run your nail over it and feel granules. I was assuming it was dirt settled in the pitting, but it may be the plaster eating away.
Man this is frustrating. and I'm sure the contractor will claim no fault and it is not likely to end if my favor if I chose to pursue.
I will try the vacuum/sock/acid test this evening when I go to clean it to confirm.
I'm not sure I know what you mean... Type of plaster? I have no idea. It's a white plaster over gunite structure. It was installed by a reputable contractor in my area.
Plaster has different types of aggregate.
The most basic is marble aggregate, which is calcium carbonate.
Then, you have quartz and pebble.
Most likely, you have plain marble aggregate.
I would estimate the amount of plaster when new would be about 2,200 lbs at about 3/16” thick.
If you lost 1,000 lbs, that is almost half.
So, that seems unlikely unless the plaster is deteriorating more now than before.
Overall, it seems like there is no obvious definite reason that the TA is increasing.
The most basic is marble aggregate, which is calcium carbonate.
Then, you have quartz and pebble.
Most likely, you have plain marble aggregate.
I would estimate the amount of plaster when new would be about 2,200 lbs at about 3/16” thick.
If you lost 1,000 lbs, that is almost half.
So, that seems unlikely unless the plaster is deteriorating more now than before.
Overall, it seems like there is no obvious definite reason that the TA is increasing.
@JamesW I thank you for your input. It is greatly appreciated. Agreed that while there is some dissolving of the plaster, certainly not close to half of it.
Perhaps it's a combination of SWCG general pH rise, and the plaster deteriorated. Still at a loss and it seems so excessive. Would increasing CH help reduce further etching of the plaster, and curb the potential impacts on pH. I mean 430 seems pretty Dang ideal to me.
Perhaps it's a combination of SWCG general pH rise, and the plaster deteriorated. Still at a loss and it seems so excessive. Would increasing CH help reduce further etching of the plaster, and curb the potential impacts on pH. I mean 430 seems pretty Dang ideal to me.
The SWG and the pH rise will not cause the TA to rise.
As long as the CSI is between -0.3 and 0.0, the CSI is good.
Something is being added or the tests are wrong.
The something might be dissolved plaster, but it seems like a lot of plaster if you are not seeing signs of obvious plaster dissolving.
Thanks @JamesW I honestly can't explain the TA rise over the past week. This is atypical behavior for sure. My TA is constantly in the 60-80 range and I rarely use baking soda. I did before I left for vacation only because I was trying to get it back to 60 before I left since I added so much MA the night before I left.
I just tested again and I'm still at 7.2/60. I'm going to perform a series of tests over the next few hours to see if it will hold. Then aerate to bring my pH back up to target. Go from there. I guess I may not have a choice but to invest in an acid dispenser if this keeps up next season.
I misspoke before. I'm running 2200 RPM with IC40 at 4% for 12 hours a day. Not 2000 RPM as previously stated.
I just tested again and I'm still at 7.2/60. I'm going to perform a series of tests over the next few hours to see if it will hold. Then aerate to bring my pH back up to target. Go from there. I guess I may not have a choice but to invest in an acid dispenser if this keeps up next season.
I misspoke before. I'm running 2200 RPM with IC40 at 4% for 12 hours a day. Not 2000 RPM as previously stated.
- Jul 17, 2019
- 4,070
- Pool Size
- 13000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
This has been an interesting read and hopefully we can solve the mystery soon. I am curious why you would want to aerate at 7.2, especially if you are battling rising pH.
I would check the pH and TA daily for two weeks to log the results on a graph to see if there is any pattern that will help us identify what is happening.
If the TA rise is from calcium carbonate from the plaster, you will get the same ppm increase in calcium hardness as you get in TA.
So, monitor the CH and TA to see if they rise by the same amount.
If they do, then that points to calcium carbonate.
How did you get an increase of 60 ppm CH in one day without adding calcium?
How did you measure a CH of 377?
So, monitor the CH and TA to see if they rise by the same amount.
If they do, then that points to calcium carbonate.
How did you get an increase of 60 ppm CH in one day without adding calcium?
How did you measure a CH of 377?
Honestly, I'm just trying to get and maintain target. Even if it costs me a fortune in acid. These wild swings are driving me crazy. You can see before I left for vacation I knocked the pH down to 7 knowing that it would rise. As you can see, it rose to over 8.4 in just 9 days. I may just sit back and watch the rise and graph the results.
The TA rose by 55 ppm from 65 to 120 ppm.
If that was caused by calcium carbonate, the calcium now should be 430 + 55 = 485.
What is the current CH?
If that was caused by calcium carbonate, the calcium now should be 430 + 55 = 485.
What is the current CH?