When to stop "acid addition & aeration" cycle to reduce TA

framcus

Member
Mar 1, 2008
5
New Jersey
I installed as SWG for the first time this season in June and followed the valuable information on this site regarding optimizing water chemistry for an SWG pool. In particular I appreciated the legacy content from Chemgeek regarding the need for different pool chemistry with an SWG.

I have enjoyed easier maintenance and clear water since installation. In fact the pool stayed clear despite 5 1/2 days without SWG/filtering due to the storm-induced power outage we experienced a couple of weeks ago in NJ.

My pool chemistry is as follows: FC 4.5-6.5 (20%-40% SWG); CYA 70; pH 7.7; acid demand 1 drop to 7.4, 2 drops to 7.0; TA 60; Na 3250; Ca 375

When I finally got new test reagents this spring I found I had a pool TA of 200, having initially used out of date and under-reading test reagents. However after a couple of months I have now successfully reduced my TA to 50 by the addition of HCl (31% MA) and blowing off CO2 through aeration as recommended. I've been using about 2 gallons a week of MA. I've reached a point where the TA drops to ~50 after reduction of pH to 7.0-7.2 and then rises to 60 as the pH rises with aeration (waterfall+slide) within 48 hours. Without aeration the rise in pH is slower, but rises nonetheless. TA also rises and measures 60-70 as it approaches 7.8 as you would expect.

Unfortunately I don't seem to have reached the optimal TA point, that many others report, where it finds a stable equilibrium. Should I persevere with the cycle of acidification and aeration and try and push the TA down to 40 or lower? Or else should I now let the pool find its own pH level (probably 7.8-8.0) and live with that?

Thoughts and suggestions welcomed...thank you.
 

bonsey

Well-known member
Oct 7, 2018
82
PA
I would leave your TA alone and dial in pH as needed with MA, both should then stabilize. The ph of 7.8 isn't necessarily a bad thing and if that's where it stays, let it alone until it gets to 8.0 or above. Normally you'd use MA to lower TA and aerate to get your pH back up again without affecting TA but your ph is good so no need to aerate. Lets see what the other experts chime in with.
 
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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
I wouldn't let the TA drop any lower than 50. Between the SWG's aeration and the addition of water throughout the season, pH and TA will increase slightly. Adding a little MA every few days is just part of the routine. This is my first SWG season and I've experienced the same. As bonsey noted, let the pH rise to about 8.0 before gently lowering it to about 7.6-7.7 as needed.