Yep! Baking Soda is Sodium Bicarbonate. It's the same stuff as "Alkalinity UP" but much cheaper. If you get the bags of it at a warehouse store, instructions for use in a pool will be on the back. New pool owner here. I had the same question, and given that the pool is a captive body of water, came to the conclusion that one simply cannot substitute Baking Soda (Sodium BiCarbonate) for a PH increaser (i.e. Sodium Carbonate) without fully understanding what affect the chemical structure difference between the two will have on the water. I enclose here some info on the chemical makeup of the two: Sodium carbonate, chemical formula Na2CO3 is less acidic, than sodium bicarbonate (baking soda), whose chemical formula is NaHCO3.
Baking soda is not the best choice as it more readily increases Total Alkalinity. Soda ash on the other hand will do an excellent job. (available at most hardware stores as an acid neutralizer)
Baking soda actually raises the total alkalinity of your pool. This does also increase your pH, but should only be used if your test kit shows low alkalinity. Otherwise you'll raise both pH and alkalinity and then have to use alkalinity down. Borax will raise PH and not alkalinity, but it raises it a lot. Start slowly by adding 1/2 box per 10,000 gal of water. Check the pH after 24 hours to see if you need more. Be sure to use only Borax and not detergent with Borax.Answer by TS( It must not contain detergent ) Only use 20 Mule Team Borax Laundry Booster. It can be found at any grocery store. 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. If your alkalinity is also low you can use baking soda 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. http://www.poolsolutions.com/gd/borax_20mule.html(copy & paste to use link)