Qb optimisation and humidity control after hps swap

Hey guys long time no post. I’ve just made the jump from traditional 600w hps to 480w qb In my 4x4 flower tent and am after some environmental control advice. The hps killed all humidity but left me with heat issues. The qb solved the heat issue but now I’m a little stumped on the rh%. Any input would be appreciated. @dbrn32 I know you’re the qb king. Have you got any tips?

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You should get best transpiration running canopy temps a little higher with qb’s, after that just try to follow vpd charts.


Ok cool. It’s currently about 25-29’C.

So the vpd chart suggests between 60 and 70%RH. This is my flower tent. Won’t this amount of moisture give me issues?


Hmm, my chart is adjusted for white leds. If I followed lines correctly I have 1.58 at 27c and 50% rh. That should be in wheelhouse anyway. And looking at the numbers, doesn’t really seem out of line.


Hey buddy, when you get time could you post the vpd chart that is adjusted for white leds? I can’t seem to find it and would be very interested in seeing it. Thank you friend!

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Thank you. Luckily that is the one I already use.

That’s the correct one, labeled as leaf surface temp cooler than air temp.

Thanks for the reply’s. it was tricky to work out at first but with my fan Speed and light height dialled in I’m getting 28’ and 50% so I’m stoked.