Thanks for the details Brian. That article rocked.
I suppose that I can run my circuit for longer periods of time safely if I was able to add one of those biocides as long as it didn't react negatively with the deionized water-antifreeze mixture.
I guess it's time to look into those additives a little more closely.
btw, I was using Prestone antifreeze. It seems to do fairly well in my circuit, but I always strive to do better if I can
Thanks again
Ice