Hi Anthony,
Thanks for coming out to Boston last week - it was a great talk, although I had to run out before the end.
Anyway, this sounds like a good system, but I don't see how it can be run truly constantly. Not sure how frequently you could have the pump go, but too frequently or in too small volumes each time and the auto-top-off would not function very well, resulting in increasing salinity. Correct?
I was throwing around an idea of potentially doing something similar to pH monitor-based CO2 injection system, by hooking up a dosing pump to a digital salinity meter (I'm no electronics expert, so have no real idea how to do this). To maintain salinity at the target leve, the pump would dose water, but it would be hooked up to brackish water rather than RO/DI, so it would need to overcompensate the evaporation to maintain salinity, resulting in excess water out the overflow drain.
Ryan