Instant clouding after adding sodium carbonate (pH+)


Well-known member
Jan 25, 2010
My chemistry was:

FC 15 (on it's way back down after shocking after a pool party)
pH 7.2
TA 100
CH 150-200
CYA 30
Water temp ~90-92

I like to keep the pH around 7.4 and usually use borax to raise pH, but was out of it, so I used pH+ (sodium carbonate) to raise the pH. When I put it in, it instantly clouded the water as it dispersed- a milky white cloudiness. It stayed cloudy all evening and by the next day it had cleared up. Did adding the sodium carbonate cause calcium to precipitate? I added a small amount of ionic clarifier just in case and by the next day it was clear. I have no idea if the filter cleared it or if it was a precipitate that reabsorbed? Any ideas? Not sure if I should use that again (even in a pinch).

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
It is fairly common to have sodium carbonate (pH Up) cloud a pool temporarily. The area where it is added gets raised in both pH and Total Alkalinity (TA) where that combination over-saturates the water with calcium carbonate causing cloudiness. As this mixes throughout the entire pool, this usually dissipates and clears as the calcium carbonate dissolves into the water unless the water is over-saturated (i.e. has a high saturation index). So you probably didn't need to use a clarifier and could have just waited, assuming your resulting pH and TA didn't get too high.