"Ken" wrote in message...
Upon doing some investigation I have realized that if people can use
hobbyist test kits or test strips to monitor pH (and thereby CO2) in a
CO2 injected tank, then I can use an electronic pH meter to control a
solinoid valve w/o spending $350 for an electrode and $1000 for a
meter. A "student" electrode (which will run me $50-$100) should do
just fine providing I calibrate it regularly, and is available from
the supply houses we use in our lab. These supply houses do not,
unfortunatly sell inexpensive pH meters w/ low pH alarms. I know
dupla sells 2 of them, but I'd like to shop around a bit. Does
anybody with an automatic CO2 system have any suggestions on where to
find one?

Ken


You might try http://www.automatedaquariums.com/index.htm

HTH