trouble with temperature and humidity

[smd1973]

Hi All,

First time grower here. I recently set up a 4 x 2 x 5 tent with a 400w HPS light that I am currently using a MH conversion bulb in. I put my seeds into rapid router on 12/26 and planted them in Fox Farm Ocean floor a few days later. I realize now that this was not the best plan, but the plants are still alive so I think thy made it through. I have a couple of problems I'm trying to remedy. One is that my tent gets really really hot. I have a thermostat under the lights kind of balanced between the 3 pots. the temperature reading is 91 degrees which I believe is way too high (70 is what I seem to recall them liking). I also have very low humidity at 23%. I put a bowl of water under the lights with the plant in hopes of creating some humidity but its not working. I have an exhaust fan that is blowing on high. Without it the tent temperature got up to 99%.

I'm thinking that I have too much wattage for my tent. Is that a reasonable guess for this problem. My plants see to be growing very slowly so I'm not sure if the improper temperature and humidity is getting to them or if it is something else. Photos attached were taken today which is Day #19. Any insight from the GWE brain trust would be much appreciated. Thank you!

[Obi-Wan]

What kind of HID fixture are you running? By this I mean is it a Gull wing, parabolic, cool tube, air cooled hood? In a 5’ tent I think you might run into height limitations but I don’t think 400 watts of HID is too much for your space as long as you have the proper reflector technology to exhaust the heat. I would recommend and air cooled hood with at least a 200 cfm in-line fan to remove the heat created by the bulb. I’d also recommend spending a little more on your bulb, higher quality bulbs produce less heat. I run a 400 watt Hid under these conditions and my tent averages 5 degrees F warmer than room temperature.

[smd1973]

Thanks for the response. I have a very basic reflector for the light. There is no cooling system built in. I had hoped that the exhaust fan would remove a lot of the heat but it’s not doing that. Any recommendations for a better bulb? This ballast reflector and bulb are about 10-15 years old and were given to me by a friend. I’d gladly buy a new bulb or air cooled hood if you have any recommendations. Thank you!

[alltatup]

Heat in the grow room was one of the reasons I switched to LED cobs in my grow room. You're right: you gotta lower that heat. Try wet towels in the grow room to raise humidity; the water will evaporate a lot faster. And this will help you:

https://www.growweedeasy.com/temperature

humidity

I'm only in my 4th year of growing, but I sure did learn my lessons about temp and humidity. It can be expensive to fine-tune your grow room so that you have the optimal conditions both for veg and for flowering, but if you don't, it will affect the bud quality. So I went ahead and invested in a big dehumidifier (mostly for flowering) and a humidifier (mostly for veg), and as I said above, switched to LED cobs. Now my grow room stays at 72 (with a little help from central air when necessary).

[oldjarhead100]

I added a light to my grow room so I am in the process of adjusting the timer on my exhaust fan so that it will keep the room at a more consistent temp, if you dont have an exhaust fan then I would add one