Question about heat in grow tent

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kingneverdies

New Member
Hi all, total newbie here doing their first grow.
I have a small 2x2x4 grow tent with:
- two plants growing, around four weeks into veg (6 nodes), no training
- a filtered exhaust vent running 18/6
- two 45w ("450w equivalent") LED grow lights on a 18/6 timer
- PPFD readings of between 600-900 on the upper leaves and down to around 300 on lowest ones.
- small oscillating fan
- RH between 58 and 62%
- LST of 23-27 C (73-80 F)

If possible can someone let me know for two things:
1. whether this RH and temp is fine for a 18/6 schedule, and
2. whether yield would be much affected if I switched down to just one of the 45w LED lights, and get around 400-600 ppfd? This decreases the LST a fair bit, so is something I'm wondering too.
 
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ec121

Well-Known Member
kingneverdies said:
If possible can someone let me know for two things:
1. whether this RH and temp is fine for a 18/6 schedule, and
2. whether yield would be much affected if I switched down to just one of the 45w LED lights, and get around 400-600 ppfd? This decreases the LST a fair bit, so is something I'm wondering too.
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1. Fine for veg
2. Yield will be terrible with a 45w light. Sweet spot for temps when using LED's is actually around 82F (28C).
 
K

kingneverdies

New Member
Hook Daddy said:
Your heat looks fine, with led lights IME 26-29 C is ideal. Don’t drop the second light, you have barely enough as it is.
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Great thanks!

See that's what I'm a bit confused about, because from what I read online, 45w is nowhere near enough, but yet when I use a proper Lux meter and convert to PPFD using the "High CRI LED 4000k" spectrum, even after carefully measuring each leaf, they are all between 300 to 600ppfd. That's with just one 45w grow light at about 14 inches from the top of the plants. Confusing!

Could it be that the recommended wattage comes from old incandescent bulbs or CFL lighting? Where there would be lower light per watt.
 
Herb & Suds

Herb & Suds

Well-Known Member
kingneverdies said:
Great thanks!

See that's what I'm a bit confused about, because from what I read online, 45w is nowhere near enough, but yet when I use a proper Lux meter and convert to PPFD using the "High CRI LED 4000k" spectrum, even after carefully measuring each leaf, they are all between 300 to 600ppfd. That's with just one 45w grow light at about 14 inches from the top of the plants. Confusing!

Could it be that the recommended wattage comes from old incandescent bulbs or CFL lighting? Where there would be lower light per watt.
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No
You need at least 100 watts actual wattage for a decent single plant grow
 
medidedicated

medidedicated

Well-Known Member
My 2x4x5 with 65w in each side. Similar ppfd and my clones just grow more fruitful with more light and space. Yours being a 4ft tall tent is even tougher IMO.

How is lst not needed with less light? This is already too bushy and suffered later chop time too. I guess makes sense if youre trying to dial things in and if you get better ppfd to your plants size then yea.

I should get more light but no use if you cant get your plants the right size /shape for such small space. Easy to under pack, hard to pack tents in.

I got a 130w same brand in my 2x2 but last time it was dim half way because 2nd time running it and didnt pack it in right.

If more light same brand doesnt get it like the mars hydro light than huh… Maybe one light does grow better weed than the other. Yea I run similar temp/rh.
 

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medidedicated

medidedicated

Well-Known Member
Oh. Well those temps are primo IMO. Perfect. If temp too hot get ac or cool the grow room with a open door with big pedistal fan blowing air in. I did that but live in the room so I have booster fan blowing air in through duct holes in the door.

That was from venting outside I had two holes. Ac started failing so cant do it in summer time but works any other time.

Lucky the door has two holes so one is blowing air in, the other passive so it doesnt effect ac. If you wanted door shut. Idk what else youd do, Move it to basement if you can. I think anything under 90F is ok.
 

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medidedicated

medidedicated

Well-Known Member
This first time hearing about land surface temp in indoor growing. Sorry trying to just help if Im not helping at all lol. I just answer threads talking about hot grow room issues. I live up north but get 95f summers and grow ground floor.

My grow room gets 90 maybe 92f once before I got it under control again thought it could apply elsewhere.
 
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ec121

Well-Known Member
medidedicated said:
This first time hearing about land surface temp in indoor growing. Sorry trying to just help if Im not helping at all lol. I just answer threads talking about hot grow room issues. I live up north but get 95f summers and grow ground floor.

My grow room gets 90 maybe 92f once before I got it under control again thought it could apply elsewhere.
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Right - air temperature is what we're concerned with as growers. It's not clear if he's talking about air temperature or taking readings with an infrared thermometer of the floor of his tent, but he should be taking readings of the canopy.
 
K

kingneverdies

New Member
ec121 said:
Right - air temperature is what we're concerned with as growers. It's not clear if he's talking about air temperature or taking readings with an infrared thermometer of the floor of his tent, but he should be taking readings of the canopy.
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LST here, leaf surface temperature, with an IR gun. Air temps around 27-28c. Sorry for any confusion.
 
medidedicated

medidedicated

Well-Known Member
That rh is relatively high but if the colas are able to breath not squished against another or tent walls, fine. Pluck leafs in balancing manner across canopy get good views of the floor through out the canopy looking from above.
 
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ec121

Well-Known Member
medidedicated said:
That rh is relatively high but if the colas are able to breath not squished against another or tent walls, fine. Pluck leafs in balancing manner across canopy get good views of the floor through out the canopy looking from above.
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I'd up the exhaust and run it 24/0 during flower.
 
medidedicated

medidedicated

Well-Known Member
Last run was pushing it but never passed 55rh really but this run is passing 60rh often so I manhandled it, pruned and defol to get it able to breathe. You can see the floor between the leafs still.

Helps with mold and finish on time with full light exposure to all sights, less light is counter productive.
 

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medidedicated

medidedicated

Well-Known Member
Ohh I thought that was their light schedule. If not running co2 yea Idk why shut off fan. Not good for mold or overheat issues. Vpd is for lights on if thats why. Id keep lung room in check whatever that took.
 
laddyd

laddyd

Well-Known Member
Judging from your temps and RH your VPD is good right now for vegging. When you go into flower you will need to either raise the temp or drop the humidity a bit.
 
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