I don't have an explanation for this. CH should not affect carbon dioxide outgassing rates as far as I know. Lower pH would increase such rates as would higher TA and increased aeration and higher SWG on-time so doing the opposite -- higher pH, lower TA, less aeration, lower SWG on-time, are the normally prescribed methods to getting more stable pH in pools using hypochlorite sources of chlorine.smallpooldad said:
Is there anthing wrong with high levels of calcium.
- Thread starter smallpooldad
- Start date
Chem Geek,
No idea either but the acid usage is definetly down, it seems to hold near a pH of 7.4, for most of the day, and might rise to 7.5 or 7.55 overnight, if the pool is uncovered , especially if it is windy, 16 to 24 mph are our normal trade winds, although the other day we had 50+ mph winds. If covered at night the pool pH pretty much holds until uncovered. Each day the required amount of acid is added to compensate for adding liquid chlorine, using PoolEquations spreadsheet recommendations as a guide, plus a little to compensate for risen pH over 7.4 if needed.
I still have not replaced the PoolPilot Digital controller as we had heavy rain up in the mountains where we live, but nice and sunny at the beach down the hill, some 2 1/2 miles (1 1/2 mile as the crow flies), and at Waikiki beach a 5+ mile drive.
This is just for info that might help you determine why the rise in pH is slow, the pool temp was around 75-78F.
No idea either but the acid usage is definetly down, it seems to hold near a pH of 7.4, for most of the day, and might rise to 7.5 or 7.55 overnight, if the pool is uncovered , especially if it is windy, 16 to 24 mph are our normal trade winds, although the other day we had 50+ mph winds. If covered at night the pool pH pretty much holds until uncovered. Each day the required amount of acid is added to compensate for adding liquid chlorine, using PoolEquations spreadsheet recommendations as a guide, plus a little to compensate for risen pH over 7.4 if needed.
I still have not replaced the PoolPilot Digital controller as we had heavy rain up in the mountains where we live, but nice and sunny at the beach down the hill, some 2 1/2 miles (1 1/2 mile as the crow flies), and at Waikiki beach a 5+ mile drive.
This is just for info that might help you determine why the rise in pH is slow, the pool temp was around 75-78F.
Didn't you say that your TA level is lower now than it was when the PH was constantly rising? That would explain everything if I am remembering correctly.
Jason Lion,
The answer is it has actually risen as I had added 20 ppm of CyA to move it from 30 ppm CyA to 50 CyA, the net effect was that the the TA moved from 50 to 60. It seems to hold there with Ca at 900 ppm.
Carbonate Alkalinity (ppm CaCO3) is at 43.0%, not sure if that has anything to do with controlling outgassing.
Hope this helps, if I wrote it any other way my apologies.
Thank you.
The answer is it has actually risen as I had added 20 ppm of CyA to move it from 30 ppm CyA to 50 CyA, the net effect was that the the TA moved from 50 to 60. It seems to hold there with Ca at 900 ppm.
Carbonate Alkalinity (ppm CaCO3) is at 43.0%, not sure if that has anything to do with controlling outgassing.
Hope this helps, if I wrote it any other way my apologies.
Thank you.
In that case the question is, how did carbonate alkalinity change? It is the carbonate alkalinity that puts upward pressure on PH.
Presumably you were adding acid before and haven't added any baking soda or soda ash/PH Up. If so, carbonate alkalinity will have gone down.
What generally happens when you stop adding baking soda is that you continue to add acid as required by the upward PH drift, bringing the carbonate alkalinity down, until finally it gets low enough that PH stabilizes.
Presumably you were adding acid before and haven't added any baking soda or soda ash/PH Up. If so, carbonate alkalinity will have gone down.
What generally happens when you stop adding baking soda is that you continue to add acid as required by the upward PH drift, bringing the carbonate alkalinity down, until finally it gets low enough that PH stabilizes.
The 20 ppm CYA would raise the TA at a pH near 7.5 by roughly 7 ppm which could show up as 10 ppm in a TA test, but this TA rise doesn't affect carbonate alkalinity so the rate of pH rise shouldn't change from before the CYA increase. So what Jason is saying is that if the TA has come down from regular acid addition and this occurred at around the same time as the CH rose, then it is the lower TA that is the cause of the more stable pH, not the higher CH.