Can you use borax to raise pH in swimming pools?

The most commonly sold product for that purpose is sodium carbonate, aka soda ash, sold as Ph Up by pool stores and as "Washing Soda" by grocery stores.

You can also use 20 Mule Team Borax Laundry Booster (sodium tetraborate). It can be found at many grocery stores. Try using the same amount as you would with PH plus 1 lb. to 10,000 gallons, and wait 2 to 4 hrs. Then check your PH reading. If it's still low, add some more until you get it to 7.2 to 7.8 range.

Caution - check your alkalinity before using borax, because borax raises PH only, without affecting your alkalinity much. If your alkalinity is also low you can use baking soda (sodium bicarbonate) to raise your alkalinity and PH. Baking Soda raises PH and Alkalinity at the same time. Baking Soda has the same ingredients as Alkalinity plus, but half the price. Take a look at this web site for more information on Borax: www.poolsolutions.com/gd/borax_20mule.html