Help with air temps - general question

[purzurples]

I built a 2' x 4' x 7' grow closet.
Actual dimensions allow for a few extra inches all around, so it's really about 2'6" by 4'6"
the walls, ceiling and floor are lined with light tight bubble wrap stuff.
it reflects all the IR.

I use a 400W MH right now on a switchable ballast and "the probably most widely known name brand white reflector hood"

The air temps Outside the closet are always at 70 degrees Farenheit. very nice.
But INSIDE the closet is where my general question is about.

Can I get some confirmation on something my gear supplier taught me?
As a first step, he said, your reflector hood's exhaust fan also can serve as your closet's exhaust. Meaning my inline fan pulls the hot air out of the closet itself by pulling it out through the reflector hood.

Anyway, temps inside the closet are at 90 degrees Farenheit, THE ENTIRE 18-hour "DAY". The 6 hours of night: temps sit at exactly 70 degrees.

Am I gonna need two fans? In other words: give the hood its own duct into the closet and give the closet its own exhaust fan? i hate that idea for some reason.
The system is a DIY aero using 5" PVC fence posts. The reservoir is not in the closet so the nutes are hovering at 70 degrees.
Just before the lights come on, the plants are extremely healthy with strong green leaves (plants are healthy). But within minutes of the lights coming on, sure enough the closet temp hits 90 and stays there, and six hours into the day the plants put their "arms down", and I know it is because they are transpiring their internal water faster than they can drink the cool res water..(i.e. heat stress).
Many times a day I just open the closet door..minimum achieved temps = 88 degrees.
I really dont want two fans but I thought I would ask before assuming to buy one.
Maybe just a more powerful one?
Does an HID setup really use the exhaust fan by exhausting all the room air out through the reflector hood?
help me, brothers and sistas, hep me! heehee.

Mike
I will be staying with HID until I can afford a plasma light. no desire for LED here.

Any insight most appreciated.

 

[Twelve12]

Re: help with air temps(general question)

Get one big fan for exhaust or two small ones one for exhaust and intake. During the Winter you may not need two for the Summer it may come in handy. If the big fan like 6 or 8 inch may do the trick by itself pulling heat through the hood or a cooltube would work. Have you thought about using Gas Lantern Routine light cycle (12-1)? It may cut down some heat with less ON hours.

 

[FrankFoster]

Re: help with air temps(general question)

Design the box for passive intake and into the box, forced pull into the light through a filter and then vent forced air out.

Add kelp based powder to the res and gelatin to the res to buffer out the heat problems and cut back on the nutes to 1/4 strength. lower you ppm to 800 range and don't get higher than 1050ppm.

If you have a few old CPU laying around, take the heat sinks out of them and aadd them to the top of your light where it seems to get the most heated.

 

[purzurples]

Re: help with air temps(general question)

Gas lantern routine: initiated.

The fan I am using is actually a 5" CPU fan which I fitted to the exhaust duct of my hood.
I'll be on gas lantern for the veg cycle and then obtain a proper inline fan.

Passive air intake is already at the bottom of the closet. The CPU fan is powerful for its size.

Funny thing: Even before seeing the photos of Twelve12's results with the GasLantern lighting routine, I already held true to the priceless value of darkness/rest in the lighting regimen. I check on my plants (and measure them) several times a day, but it is really only after the darkness period that I witness noticeable growth.
I'm pretty excited about doing the GLR. I believe plants do most of their actual growth during their rest period in the dark, and that the roots do their growth during the light.
It's that little extra hour of light in the GLR that keeps their genetics thinking "veg". Pretty brilliant actually. Confident here that this lightDark pattern will benefit growth.

Since GLR is apparently rarely-used, I will post follow up results in here (evem if nobody else is interested lol).

Thanks.

 

[mudrunner]

Re: help with air temps(general question)

NOOB QUESTION!... what is gaslantern lighting? would anyone care to expand on this at all?

 

[Twelve12]

Re: help with air temps(general question)

NOOB QUESTION!... what is gaslantern lighting? would anyone care to expand on this at all?

Check out this blog post.

 

[Twelve12]

Re: help with air temps(general question)

purzurples ~ Glad you got it under control. Good luck with the GLR! Looking forward to the results.

 

[PotChimp]

Re: help with air temps(general question)

2.5 x 4.5 x 7 = 78.75 (cubic feet of your grow room)
78.75 x 5 = 393.75 cubic feet per minute (# of recommended room air changes per minute)
A 400 cfm fan, in other words. That's what I'm going to do in the long run (or bigger), because I am eventually going to increase lighting in my grow closet to 600 watts and will have the same problem. Mine is just a baffled vent air input (to keep light out); no fan. Output is now a 4" inline fan with a carbon filter (170 cfm). I know that it will not handle the heat increase, so I will have to go to a 6" at least.
Good luck.