Thanks all, here's the latest:

I put in a gallon of muriatic, let it run for 2 hours, got the pH to the light end of 7.2 (using Taylor kit). Just added in 1/3 gallon of muriatic to get it to drop down to the 6.8 range. BUT, before I added additional acid, I measured the alk and it said it was down to 140. Yay, Progress!! The thing is, I had a 130 on Friday morning, and then by Friday evening, it was back to 190, so I don't trust these low numbers that I get. Think I might have some errors in my methodology...

New muriatic has been circulating for a couple of hours, and then I'm going to fire up the fountains over night to see (hopefully) a lower alk # in the AM.

Michael, I apologize for not giving you proper credit for your calculator in my earlier post. It is a godsend. Thank you.

I appreciate the warning on not going too low on pH--my kit only goes down to 6.8. I'm going to *assume* that I'm there right now and just aerate like crazy tonight so I don't damage anything.

Thanks Everyone for all the helpful info! I'll post again tomorrow w/ the new numbers.