So when we are talking temperature.........

I would never doubt your grow's cooling capabilities desertrat. Sounds like you spent alot of time working through the details.

Sounds sweet

Like a hid put your hand under the light see how close you can get it without burning your hand. thats how close you can have them. I keep my 400w hid about 6-8" of the top of my plant. I could be closer but don't need to be. hid and vented hoods are great. then run the room 75-85. lol still not metric. or 15cm-20cm and 24c-29.5c I think

I am right in thinking you are running far more than a cooled hood to get that light that close?

Loved to see a pic of your set up if you have it handy.

Just a cooltube. It has helped temps a bunch. here is the diy cooltube.

pretty awesome

It could be beter but thats what I had to work with. I get as good or beter light then with a 1000w with out a vented hood.