Maintaining a balanced swimming pool pH is a vital part of swimming pool maintenance. Not only does the proper pH protect your metal fittings and the walls of your pool, but the right pH range is also what makes swimming in the water pleasant instead of an itchy, burning trial. The correct range for a swimming pool is a pH of 7.4 to 7.8. If you are testing your pool and the pH registers as too low, try the techniques below to raise your pH.
1. Check Your Reagents
The first thing to check when your test indicates a low pH is whether your test reagents are still good. Reagents should be replaced every year and should never be mixed between test kits. If your kit is old, try getting a new one and testing again.
2. Add Soda Ash
If your pH is still low, try adding sodium carbonate, commonly called soda ash. Never add more than two lbs of soda ash per 10,000 gallons of water in your pool in any single treatment. Distribute the soda ash over the whole of the pool surface, starting in the deep end. Make sure that the pump is circulating to distribute the water and then wait an hour or so before testing again. If the pH is still too low after an hour, you can add more soda ash.
Soda ash may cloud the pool water at first, but this should fade out within a day or so.
3. Check Your Total Alkalinity and Add Baking Soda
If the pH in your pool continues to drop even after you attempt to raise it, test your total alkalinity. Low total alkalinity will allow the pH to fluctuate randomly. This number should be in the range of 80 ppm to 150 ppm, so if your test shows it is low, add 1.4 lbs of sodium bicarbonate (baking soda) per 10,000 gallons of water in your pool. This should raise the total alkalinity by 10 ppm. Again, let the water circulate for an hour or more before testing again. Baking soda will raise the pH slightly, but its main effect is in raising total alkalinity. Be careful not to add to much baking soda as it is much harder to lower total alkalinity than it is to raise it. Soda ash will also raise the total alkalinity, so always check this number after each step when trying to raise your pH.
4. Aerate to Raise pH
Another trick for raising pH is aeration. If you have any pool water features, turn them on. Point water jets towards the surface or add pipes over jets to direct the water to the surface—anything to get the water moving around the surface. This will drive carbon dioxide out of the water. Aeration will raise the pH in your pool without affecting the total alkalinity. This process can take several days but is very effective with pools that have otherwise been stubborn in maintaining a low pH.