You sure can. Just be careful handling it. Pool Math does not have an automatic calculation for sodium hydroxide but you can get an estimate of how much to add using the Effects of adding chemicals section at the bottom of the page. It's listed there as "caustic soda" which is another name for sodium hydroxide or lye. Be sure to enter your actual pool volume at the top of the page before using the Effects section.
+1 I find it more hazardous than handling muriatic acid. The dry form that's usually only found in laboratories is even worse as it's very hygroscopic and generates lots of heat on contact with water.
If you want a direct substitute for soda ash (sodium carbonate), it is Arm & Hammer Super Washing Soda (careful: NOT the laundry detergent).
20 Mule Team Borax raises the pH with about half the rise in TA compared to sodium carbonate. Lye (caustic soda) is more pure and doesn't increase borates. Aeration raises the pH with no change in TA.
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