Thanks all! 2-3 bps drops my Ph from 7.6 to 6.9. Not a hugh amount of CO2, but enough at a safe rate while I wait to get my controller back. The tank has 8 adult discus (2 spawning pairs) that I raised from half dollar size. They are really nice specimens and though I generally defer to plant haelth first, in this tank, I have to be careful to protect the discus. None of my other tanks has a controller. I really am surprised that 2-3 bps adds that much CO2....