The water thought occured to me too. But wouldn't RO/DI deal with chloramine if it was present?
Interesting about the borate/alkalinity connection .. hmmmm, will have to do some reading on that one. I'm right now using a bucket of Kent, was using IO before that. I've sort of bounced between IO and Kent over the years.
I have run carbon off and on. When I do run it, I have a small amount in a Phosban reactor and try to change it out every week or two. Also, same with the Phosban, I do have some on right now. I'm not sure how to tell when it's time to change it out. People say they change it out when their phosphate levels start going up, I have yet to detect an upward trend when I test PO4. I'm never sure if this means PO4 is OK, or just if my test methods are inadequate. Maybe it's time to buck up and pay a lab to do a chemical workup, if for no other reason than I can maybe express some confidence in the #'s I do come up with.
