I am far from recommending this method. I am mainly posting it to get some Other opinions from it. It worked really well for Me; I couldn't believe how well it worked.
My alkalinity was 190, and My PH was 7.2
The method I found (online in a couple of places) said turn off the pump, let the water currents settle fully; go to the deep end (if You have One) and SLOWLY pour about 1/4 cup of CYA in one spot. Do this in 3 or more spots. Do this away from the sides of the pool. If You have an above pool with no deep end, then just pour more columns of smaller amounts. Wait for 30 minutes or so, then turn the pump back on.
What this does is make vertical columns of highly acidic water that burns the Alkaloids out of the water.
What it did for Me was with One treatment, got My TA down to 100, and the PH dropped to 6.9 - 7. this was with about 1 1/2 cup of CYA.
Has anyone else tried this?
POOL SPECS: In-ground vinyl; 18 x 36' 24,000 Gallon,
Last edited by waterbear; 08-04-2011 at 05:48 PM.
11.75'x23.75' kidney 6.5K gal IG fiberglass pool/300 gal acrylic spillover spa combo; Aqualogic automation/SWCG; Pentair Clean and Clear 150 cart filter; 1.5 hp uprated 2 spd Pentair Whisperflo pump; PF:17
Retired pool store and commercial pool maintenance guy.
What are you using for testing the TA? Are you using a Taylor K-2006 test kit? Did you turn on the pump and remix your water before measuring the TA again? Did you mean Muriatic Acid instead of CYA? Did you mean 1-1/2 gallons instead of 1-1/2 cups which would hardly be able to be poured in multiple places into columns?
To actually lower the TA from 190 ppm to 100 ppm in 24,000 gallons would take about 4-1/3 gallons of full-strength Muriatic Acid (31.45% Hydrochloric Acid) and it would not matter how you added it, the TA would drop by the same amount. The difference would be in what happens to the pH and in damaging pool surfaces.
You could very well have added 1-1/2 gallons of Muriatic Acid and if you added enough in one place with the pump off then the TA in that place can certainly drop a lot, even to 100 ppm, but that is not the same thing as having the TA drop everywhere in the pool by that amount. Measure the TA again after turning on the pump and thoroughly mixing the water. 1-1/2 gallons of acid would lower the TA from 190 to about 160 ppm in 24,000 gallons.
This is nothing more than the discredited "Column" method of T/A lowering.
Frankly, I find the method and results difficult to accept, and chem_geek and waterbear are two of our best on T/A chemistry.
Are you sure of your chemicals and how you ran your tests? When pH drops, TA does as well, but a .3 drop shouldn't be enough to resolve a TA difference of 190 down to 100.
16'x40' rectangle 19K gal AG vinyl pool; ; Hayward T210 sand filter and 2 Speed Superpump 1hp pump; Solar heated. Test kit: PS 233; PF:6.3; Autopilot SWCG