muriatic acid, OK for carb soaking?

As previously mentioned, it is used to lower the pH in pools as needed. I keep a couple gallons on hand and dump some in when called for. You do NOT want to have your nose over where you're pouring it in and for heaven's sake wear safety glasses in case something splashes back at you! I put maybe 1 to 1-1/2 qts in at a time in a 9500 gallon pool.