Stumped on ventilation issue.

TrichomeChaser said:

whats up everybody. Got a lil issue going on and I’m going away for a couple days so I gotta figure it out in the next couple hours. Help please haha so I have a 10x10 tent. 2 weeks into flowering now and I just added a 3rd 600w hps a couple days ago. I’m only using half of the tent right now so it’s 5 plants scrogged on a 4x8 table. 1800w of hps. 1 oscillating fan and 2 424cfm 6inch in-line fans. The plants really took off before I started flowering so they got a little taller then I wanted. The lights are as far up as they can go and the tops are between 6-10 inches from the lights I’d say.

My issue is before I added the 3rd light my temps were sitting good during lights on in the high 70s and dropped about 10 degrees at lights off. And I was running the exhaust at about half power and opened some lower fan ports to bring air in. With the 3rd light that was not enough and temps were climbing up to mid 80s at the point of canopy that’s closest to the light.

So I added the other fan as an intake. Cranked the exhaust to full power and have the intake on Little less power then the exhaust. But my canopy temp isn’t dropping still.

I’m assuming that it’s just because they are closer to the plants then they should be and are not in air cooled hoods.

It’s directly under the light at the canopy that is hitting 86-87 at times during lights on. Off to the side a little bit it is more like 82ish. So the actual room itself the temp is not bad. And the humidity is controlled so that won’t be an issue. I’m concerned about the canopy though. They are not burning or anything but I don’t want them to hermie on me or anything from the heat everyday.

Any suggestions on how I can get the canopy temp to drop a little more?

Should I get another oscillating fan in there to keep the air moving more over the plants?

I’ll happily take any input because as I said I am going away in about 4 hours so I don’t have a lot of time to make changes!

Appreciate any advice

Thank you in advance

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Renfro said:

Move all the air you want, youre not gonna get rid of that infrared light. If you are leaving I suggest turning off the added light until you can get back and maintain things. Other than raising the lights I don't really have a good solution. Also if the lights are too close you will likely get airy tops, not nice dense ones, because of the light intensity.

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SatIndy said:

Hi @Renfro Why does light intensity (from lights too close) produce airy tops? What's going on in the plants for that to happen? Thank you

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TrichomeChaser said:

whats up everybody. Got a lil issue going on and I’m going away for a couple days so I gotta figure it out in the next couple hours. Help please haha so I have a 10x10 tent. 2 weeks into flowering now and I just added a 3rd 600w hps a couple days ago. I’m only using half of the tent right now so it’s 5 plants scrogged on a 4x8 table. 1800w of hps. 1 oscillating fan and 2 424cfm 6inch in-line fans. The plants really took off before I started flowering so they got a little taller then I wanted. The lights are as far up as they can go and the tops are between 6-10 inches from the lights I’d say.

My issue is before I added the 3rd light my temps were sitting good during lights on in the high 70s and dropped about 10 degrees at lights off. And I was running the exhaust at about half power and opened some lower fan ports to bring air in. With the 3rd light that was not enough and temps were climbing up to mid 80s at the point of canopy that’s closest to the light.

So I added the other fan as an intake. Cranked the exhaust to full power and have the intake on Little less power then the exhaust. But my canopy temp isn’t dropping still.

I’m assuming that it’s just because they are closer to the plants then they should be and are not in air cooled hoods.

It’s directly under the light at the canopy that is hitting 86-87 at times during lights on. Off to the side a little bit it is more like 82ish. So the actual room itself the temp is not bad. And the humidity is controlled so that won’t be an issue. I’m concerned about the canopy though. They are not burning or anything but I don’t want them to hermie on me or anything from the heat everyday.

Any suggestions on how I can get the canopy temp to drop a little more?

Should I get another oscillating fan in there to keep the air moving more over the plants?

I’ll happily take any input because as I said I am going away in about 4 hours so I don’t have a lot of time to make changes!

Appreciate any advice

Thank you in advance

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coreywebster said:

Try measuring air temp in the shade and not putting a thermometer under 1800w of light, you might find your air temps are a good few degrees lower than you think.

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Renfro said:

But all that matters is the canopy temp.

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Renfro said:

Move all the air you want, youre not gonna get rid of that infrared light. If you are leaving I suggest turning off the added light until you can get back and maintain things. Other than raising the lights I don't really have a good solution. Also if the lights are too close you will likely get airy tops, not nice dense ones, because of the light intensity.

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stretch1961 said:

I had temp issues and added more cfm on exhaust. Suck it out faster. Went from 83-84 to a constant 77.7-78.4.

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Renfro said:

6 inch blowers do seem small for a 10x10 tent. If you want to exchange air 3x a minute to keep the tent cooler you need something like 2400 CFM on the exhaust. Two 12 inch blowers on the exhaust MIGHT get the job done.

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joe9000 said:

agree with above,turn off extra light until you get back and sort things out,not worth a chance of frying them.

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coreywebster said:

Hmm. I cant tell if your been sarcastic?
If canopy temp matters use the hand test, if leaf temp matters use a laser thermometer, if air temp matters measure air temp correctly. Air temps are the temps we aim to be in range since plants can take radiant heat of up to 50 degrees C.

You can always roughly read air temp at canopy using a thermometer under white card and air circulated.

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Renfro said:

Also ambient temperature has a lot to do with it, hard to cool a tent with warm air. If the tent in a cool room or is it heating the room up with exhaust?

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Smitty42088 said:

With that many hps it’s always a good idea to get vented hoods especially inside a tent just my opinion..It deff made it easier on me.My first hps light was a bitch to control but once I got vented hoods it was all good..Good luck man.

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