[dmforcier]

Hey, I told (more than once if I recall correctly) how to check if your roots are being affected by the wet. You pop the soil ball out of the pot and check if there are nice white healthy roots all the way down and around the bottom. (Gotta give a transplant some time to grow them first. - and of course you won't be able to do that with your tubs so moisture meter -- they're cheap.)

You've not done that. All you've done is defend your practices that are producing less-than-optimal results.

As for the cool chamber, if you're going to go through with it, I think your water circulation technique is the better option. The biggest problem with the current design is the heat in the growing chamber - ambient heat pulled in by the ventilation fans, and heat from the lamps. Closing the chamber and using the fans to circulate the air inside might be enough to let the radiator do its thing. Adding a transparent ceiling and another set of fans to independently cool the lamps is a more radical modification if it isn't.