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Cappycat,Wow! 2 lbs of PH- is far too much, for a 500 gallon or less spa. Typical increments are usually 2 oz, not punds. It could take almost 2 lbs of PH+ to get it back up.
I'm going to drain the water and start over. I'm not going to do another thing until my husband gets home. He can take over and fix my mess...LOL!Hey, at least I've provided humor for the day for everyone reading this!