Plants are growing fine but trying to reduce the ambient 90F...

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bluegill

Well-Known Member
Setup:
2ftx4ft tent @ 5ft tall on a 2ft stand. RDWC with 5gal reservoir underneath and 5gal buckets - the buckets are black; 3.5 inch net pots, large airstones. I have a Phantom Pheno 440w LED on an 18/6 hour cycle. Vivosun 4" duct exhaust fan.

Plants:
2 indicas (black cherry OG) growing in a 2x4ft tent a la RDWC 5gal buckets. I'm seeing insanely fast growth. They were just seedlings a week ago and already have 5 nodes of growth; the largest leaves are >2 inches. They have been on GH nutes on mild/medium strength for about a week, and I have my LED set about 32" above the top of the netpots because of how young these are.

Heat Problem:
The tent was running at ~82F when I was running the light @ 80% power, but since I'm seeing such nice growth, I decided to run it full power. The problem is that in such a small tent, this increased the ambient temp at plant level to 86F, and the temp above the light to 100F. I put a large box fan in front of the intake, thinking that might help, but it only normalized the ambient temp to 90F. I read around online for a quick solution - I hung a damp towel behind the fan, and that has since dropped the temp to 88F. Just checked water temps. They are a 82F with the light on.

Potential Solutions? :weed: :bigjoint:
-I found a chart that seems to imply the ideal RH for this temp would be about 80% and that would further reduce the issues?
-With my next water change, I am going to swap the 5gal reservoir for a 20gal tote I originally intended to use - hopefully the water temp will go down, and that may also reduce the temp in the tent?
-I'm also planning on covering the black lids with a white plate to further reduce water temps. Worth it?
-I'm considering just dimming the light down to 60-80% and just lowering it. I just haven't found the sweet spot yet, as it's a new light. I stressed the seedlings out a bit with it at first.
-My last resort is to either add an immersion or external water chiller.

Is there anything else you would suggest to help reduce the heat?
 
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bluegill

Well-Known Member
lusidghost said:
I would dim the lights. That's a lot of power in a small, short tent. Maybe get a bigger exhaust or double it up? Can you drop the temp of the room that the tent is in? A portable AC would work, that that seems like overkill.
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My one concern with dimming the lights is reduced spectrum. Unfortunately, can't cool the room any lower. It's in the wash room where the HVAC is housed - but that's actually the coldest room in the house.
 
lusidghost

lusidghost

Well-Known Member
bluegill said:
My one concern with dimming the lights is reduced spectrum. Unfortunately, can't cool the room any lower. It's in the wash room where the HVAC is housed - but that's actually the coldest room in the house.
Click to expand...
That's a HID issue I think. LEDs are fine. I dim mine from veg until the buds look like they can handle full power. Sometimes I keep them dimmed all of the way through if my plants get too tall.
 
O

oill

Well-Known Member
bluegill said:
Setup:
2ftx4ft tent @ 5ft tall on a 2ft stand. RDWC with 5gal reservoir underneath and 5gal buckets - the buckets are black; 3.5 inch net pots, large airstones. I have a Phantom Pheno 440w LED on an 18/6 hour cycle. Vivosun 4" duct exhaust fan.

Plants:
2 indicas (black cherry OG) growing in a 2x4ft tent a la RDWC 5gal buckets. I'm seeing insanely fast growth. They were just seedlings a week ago and already have 5 nodes of growth; the largest leaves are >2 inches. They have been on GH nutes on mild/medium strength for about a week, and I have my LED set about 32" above the top of the netpots because of how young these are.

Heat Problem:
The tent was running at ~86F when I was running the light @ 80% power, but since I'm seeing such nice growth, I decided to run it full power. The problem is that in such a small tent, this increased the ambient temp at plant level to 86F, and the temp above the light to 100F. I put a large box fan in front of the intake, thinking that might help, but it only normalized the ambient temp to 90F. I read around online for a quick solution - I hung a damp towel behind the fan, and that has since dropped the temp to 88F. Just checked water temps. They are a 82F with the light on.

Potential Solutions? :weed: :bigjoint:
-I found a chart that seems to imply the ideal RH for this temp would be about 80% and that would further reduce the issues?
-With my next water change, I am going to swap the 5gal reservoir for a 20gal tote I originally intended to use - hopefully the water temp will go down, and that may also reduce the temp in the tent?
-I'm also planning on covering the black lids with a white plate to further reduce water temps. Worth it?
-I'm considering just dimming the light down to 60-80% and just lowering it. I just haven't found the sweet spot yet, as it's a new light. I stressed the seedlings out a bit with it at first.
-My last resort is to either add an immersion or external water chiller.

Is there anything else you would suggest to help reduce the heat?
Click to expand...
Put the duct for the exhaust directly above the light
 
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bluegill

Well-Known Member
oill said:
Put the duct for the exhaust directly above the light
Click to expand...
The exhaust and filter are above the light, but just off center. Will centering it make that much of a difference? How close should it be? Maybe I should just raise the light up as far as it will go to the filter/fan if I run it full power?

I may have spoke too soon - the temp has further dropped to 84F. Maybe just adding an immersion chiller will be all I need? I would also consider upgrading the exhaust fan. I have huge 6 inch fan - it just needs a new filter. Any idea where to just buy a filter unit? Maybe a 4" to 6" duct adapter would be enough with the 4" filter?
 
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Milky Weed

Milky Weed

Well-Known Member
bluegill said:
My one concern with dimming the lights is reduced spectrum. Unfortunately, can't cool the room any lower. It's in the wash room where the HVAC is housed - but that's actually the coldest room in the house.
Click to expand...
Look at it this way, i keep my light high and bright to INCREASE heat in my tent, it allows more total wattage and btu by allowing my lights to be turned up high far away.

It would really help to lower them and turn down, i know it dosent feel ideal, but sometimes we make due. It sounds like you have it going near perfect besides the high rez temp.

Im going to be honest here, besides your water temperature everything actually sounds really good, with LED you want heat when your pushing alot of light on them.

I dont know a ton about water hydro, but the shoot zone sounds like its doing well.
 
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bluegill

Well-Known Member
Milky Weed said:
Look at it this way, i keep my light high and bright to INCREASE heat in my tent, it allows more total wattage and btu by allowing my lights to be turned up high far away.

It would really help to lower them and turn down, i know it dosent feel ideal, but sometimes we make due. It sounds like you have it going near perfect besides the high rez temp.

Im going to be honest here, besides your water temperature everything actually sounds really good, with LED you want heat when your pushing alot of light on them.

I dont know a ton about water hydro, but the shoot zone sounds like its doing well.
Click to expand...
Thanks for your input, which is very reassuring. My only concern with heat is really ending up with foxtailing/larfing buds, which I have had happen before with rando bagseed genetics. Maybe it won't be so much a problem on a 12 hour light cycle, though?

Agreed, my reservoir temps are concerning me. I thought of a couple more solutions to that, apart from covering the lids with a white sheet. First, removing the air pump from the tent, second moving to my larger reservoir tomorrow. Lastly, sort of a last resort, would be pulling my submersible pump out and running it eternally or replace it with an external pump - main concern there is leaks outside of the tent, especially with a larger reservoir.. Not sure if it will make all that much difference with a larger water volume to make that change.
 
visajoe1

visajoe1

Well-Known Member
what is the ambient temp of the room? agree with @lusidghost you can afford to dim the lights a bit, plenty of wattage to spare. dimming doesnt affect LED spectrum, thats a HID thing.

if you're exhaust fan is at 100% and still cant maintain temps, sounds like the room itself is a bit warm
 
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bluegill

Well-Known Member
The ambient room temp fluctuates bc of the HVAC - it's avg about 72F. There is a duct without a register blowing near the tent that probably ain't helping. I think at the very least, I will add an adjustable register and blow the heat away from the tent. I actually drilled a 4 inch hole in the wall and have aluminum ducting pulling air from outside of the washroom because the cat's litter box is in there and I don't want catshit weed. No intake fan - so the 190 CFM from my exhaust fan is kinda wimpy.

I've been working on this sucker all evening guys. 1/4" sheet PVC cut into lid covers. Holy shit, under the light they are making me snow blind! No more light heating my buckets up though. :cool: I swapped the reso - before the swap, I think the total water volume was about 10 gallons, and now it's more like 20 gallons. I cut some new air tubing and also moved the air pump out of the tank.

I am running the light at 80% power now because unfortunately one of the plants has a couple of top leaves where the edges near the stem are slightly upturned - presuming heat stress. Not going to add nutes until the temp is in range. But I also have some enzymes I am going to use just as a precaution. It probably needs more time before I am confident on the numbers - the tent is sitting at 80F right now, but I added water that was 58F when I swapped.
 
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Milky Weed

Milky Weed

Well-Known Member
bluegill said:
The ambient room temp fluctuates bc of the HVAC - it's avg about 72F. There is a duct without a register blowing near the tent that probably ain't helping. I think at the very least, I will add an adjustable register and blow the heat away from the tent. I actually drilled a 4 inch hole in the wall and have aluminum ducting pulling air from outside of the washroom because the cat's litter box is in there and I don't want catshit weed. No intake fan - so the 190 CFM from my exhaust fan is kinda wimpy.

I've been working on this sucker all evening guys. 1/4" sheet PVC cut into lid covers. Holy shit, under the light they are making me snow blind! No more light heating my buckets up though. :cool: I swapped the reso - before the swap, I think the total water volume was about 10 gallons, and now it's more like 20 gallons. I cut some new air tubing and also moved the air pump out of the tank.

I am running the light at 80% power now because unfortunately one of the plants has a couple of top leaves where the edges near the stem are slightly upturned - presuming heat stress. Not going to add nutes until the temp is in range. But I also have some enzymes I am going to use just as a precaution. It probably needs more time before I am confident on the numbers - the tent is sitting at 80F right now, but I added water that was 58F when I swapped.
Click to expand...
Make sure your protecting your eyes man! wear some shades if your not.
 
PSUAGRO.

PSUAGRO.

Well-Known Member
Are you running a filter? Cause a crappy vivosun 4 inch cfm will be greatly reduced and completely underspecd for a 2x4 with 450w.
 
Herb & Suds

Herb & Suds

Well-Known Member
bluegill said:
The ambient room temp fluctuates bc of the HVAC - it's avg about 72F. There is a duct without a register blowing near the tent that probably ain't helping. I think at the very least, I will add an adjustable register and blow the heat away from the tent. I actually drilled a 4 inch hole in the wall and have aluminum ducting pulling air from outside of the washroom because the cat's litter box is in there and I don't want catshit weed. No intake fan - so the 190 CFM from my exhaust fan is kinda wimpy.

I've been working on this sucker all evening guys. 1/4" sheet PVC cut into lid covers. Holy shit, under the light they are making me snow blind! No more light heating my buckets up though. :cool: I swapped the reso - before the swap, I think the total water volume was about 10 gallons, and now it's more like 20 gallons. I cut some new air tubing and also moved the air pump out of the tank.

I am running the light at 80% power now because unfortunately one of the plants has a couple of top leaves where the edges near the stem are slightly upturned - presuming heat stress. Not going to add nutes until the temp is in range. But I also have some enzymes I am going to use just as a precaution. It probably needs more time before I am confident on the numbers - the tent is sitting at 80F right now, but I added water that was 58F when I swapped.
Click to expand...
Reducing power is supposed to be good on preserving LED longevity
 
B

bluegill

Well-Known Member
PSUAGRO. said:
Are you running a filter? Cause a crappy vivosun 4 inch cfm will be greatly reduced and completely underspecd for a 2x4 with 450w.
Click to expand...
I agree it's not adequate for my current setup. The filtration works well, but that's all. Is there a place where I can buy replacement carbon filters? I had bought my 6" used - still works great (440 CFM - just loud), but the filter smelled like ass and cigarette smoke.
 
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bluegill

Well-Known Member
Just had a thought - I could run my exhaust without the filter for now and add the heavy duty one during flower when filtering is actually needed. Maybe that will cool it enough? Sorta wasting the filter by running it now anyway. Maybe run my 4 inch as my intake and have it outside of the tent as well - would help cool down even more.
 
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