Quote Originally Posted by cropwell View Post
If all you are looking at is corrosion inhibition, how about something like Fernox - used in central heating. I haven't researched it, this is just tossing an idea into the pot.
An excellent suggestion, used with DI water that should cover all the bases, don't use bleach, if you need an anti-biological it needs to be PH neutral, but you could run your coolant through a pond/aquarium UV unit on it's return to the tank to keep the biological load to a minimum or you could have a submersible UV unit in the tank.