Is 90 degrees too hot for pot

[Dougmc]

Hi everyone first post and I already need help.My grow tent is 2x4x7 feet, in my basement, I have 3 Cinderella 99 plants growing 8 inches tall, I have an in-line fan and scrubber on low setting, 600 watt hps lights , a small fan to cool the lights and a small fan on the ground for circulation, my problem is I have 92 degrees and 30 % humidity with a humidifier in the tent on low. What to do ?
Do I buy new lights ? if so which ones for my tent and best yield. Help a Canadian out. Thanks...

 

[Chris Scorpio]

600w HPS is pretty big for that tent, I used one in a 4x4 tent

Does the HPS have a ducted hood on it?

Can u dim the HPS?, Mine had a dimmer on the balast and could drop it down to about 400w

Other option is to open the door more often, but can be a challenge in flowering

 

[Dougmc]

600w HPS is pretty big for that tent, I used one in a 4x4 tent

Does the HPS have a ducted hood on it?

Can u dim the HPS?, Mine had a dimmer on the balast and could drop it down to about 400w

Other option is to open the door more often, but can be a challenge in flowering

Thanks for you quick response.
I did just that, I lowered it down to 400 watts , raised the lights 6 inches , placed a fan in the duct and opened a vent, as well as bumped up the output of the exhaust and for 3 hours now I’m holding at 49% humidity at 82 degrees. That should be ok do you think. Thanks

 

[Blew Hiller]

92F is not too hot as long as they can rebound in the 24 period to a lower temp, say 75F, for a few hours.

What is the ambient temp of the basement? If it is around 70-75F then consider opening a lower and upper vent and using convection to cool the tent (this assumes you aren't worried about odor though).

Also don't raise the lights too much...plants want light to grow...as they grow, they get stronger and will be able to deal with your temp issues

 

[Dougmc]

92F is not too hot as long as they can rebound in the 24 period to a lower temp, say 75F, for a few hours.

What is the ambient temp of the basement? If it is around 70-75F then consider opening a lower and upper vent and using convection to cool the tent (this assumes you aren't worried about odor though).

Also don't raise the lights too much...plants want light to grow...as they grow, they get stronger and will be able to deal with your temp issues

The lights are 22 inches from the top of the plant the temp is now fluctuating between 78 and 80 which I’m happy with humidity at 44% the plants are 8 inches tall at 5 weeks old, when should I put them on 12 hour lighting, god I ask a lot of questions lol.

 

[Blew Hiller]

Pics always help. Since you went and reduced the light output, consider getting the light closer to the plant. They will let you know what is too close (burning or tacoing) but until that happens you are wasting light potential. Drop it 6" for 3-4 days and see how they respond.

 

[Dougmc]

Pics always help. Since you went and reduced the light output, consider getting the light closer to the plant. They will let you know what is too close (burning or tacoing) but until that happens you are wasting light potential. Drop it 6" for 3-4 days and see how they respond.

I will do that and get back to you with pics , thanks for the help , it seemed to have worked

 

[Grassmaster]

If they're young plants keep that light away from them. Especially bulb type lights (like HPS or CMH) that radiate IR heat. The temperature should be about 78 degrees especially with bulb type lighting. If you have them contained in a small area you need a fan to blow the hot air (at the top of the tent) out of the tent.

When I have heat problems I use COB lighting. Way more efficient. Higher PAR readings with less wattage. You need to get some type of light meter to be sure how far away the lights should be. 300- 400 watts of Cobs would be plenty of power for your tent.

I just removed my SunSytem CMH and put my 4 COB dimmable system back in my 3' by 3' tent. When it's super cold I use the CMH. But now the temperatures are creeping up.

 

[Blew Hiller]

If they're young plants keep that light away from them

5 weeks old

 

[TorturedSoul]

Yeah, but at only eight inches tall, possibly somewhat "young for their age?"

With a bright light, normal ambient CO₂ levels, good ventilation, and easy access to water for transpiration, you should be fine in the mid-80s. Watch for unusual stretching, but I wouldn't expect to see it if the plants are able to self-cool to some extent.

With it on its 600-watt setting, strong healthy plants, and the above, in an eight square foot tent, probably upper 80s. But I'm guessing you'd be at the point where you might need to add CO₂ to see 100% performance from 75 watts per foot². Grow sativas .