A question from a fellow grower:
And I’ve got a question too. I have a tent 90x90x160cm. 4plants inside
and 150W HPS. Everywhere I read I finds information’s that I should
have 400W HPS. But with mine 150w temp appears round 29C and when fan
is working 24-25C. Is it not enough?
HPS lights put out a lot of heat and need to have really good ventilation to suck the hot air out and let cooler air in. Yes, 400 is pretty much the minimum for .8 sq meters. It’s the biggest reason I switched to LED’s. I have much less problem keeping them cool.
You really should be OK with what you have. You can get it closer than a 400w, and the reflectiveness of the tent should help boost the reflectivity. It is really a matter of choice. I use a 400w, but I also have a 6" vortex exhaust fan.
Another thing. If you are in AC’d room, you can easily draw cool enough air to upgrade your lamps. Meanwhile I would go with whatever is easiest for you to keep temps in check. Peace