An (almost) closed loop garden in a tent

[YYCannabis]

Hey, y’all.

Been a while since I’ve been here at GWE. Last garden was such an abundance I haven’t needed to grow again until recently. My mantra with my garden setup has always been to add/upgrade *something* with the start of each new grow. This time around, I’ve decided that i would invest in temperature control.

After some searching around, i found what i believe is the best option for a tent or small grow room. The big green and black box sitting on the shelf is marketed as a portable Air/con for camping and tenting. This is not just an ordinary air conditioner, but is actually a mini-split heat pump system combined in one unit. The grill facing the camera is the air intake and exhaust for the tent. This circulates and cools the air within the garden without creating a push-pull air flow into and out of the space. There are two vent ducts that can be seen coming from the rear of the unit. These push/pull air outside of the tent and do not change the garden environment. The lower vent pulls-in air, from the room my tent is in, and then the upper vent is ducted outside as the exhaust temp is >45C. I’m not sure how it will impact the humidity in the tent and my VPD. I’ve been running a single disk ultrasonic water vapor unit trying to get the humidity up (bottom shelf grey pail) but it’s undersized and i regret not getting a unit with more emitters to help raise the RH faster when i need it.

** I’ll do a pros n cons in the next post**

As you can see in the pics, my garden is in flower, and is a bit chaotic in plant heights so far, so i had to adjust my lights to an extreme angle to get top-down and sideways light direction. (I really hope the plant on the right slows down, or the others grow up quickly LOL). The plant on the left was germinated about 10 days behind the others, so it’s behind in growth so far. All are autos, (left to right) White Widow, Cake Crasher, Donny Burger, and finally Bubba White (The tall girl). Sadly, the White Widow had a sickly moment after germination and now has a bent trunk.

[YYCannabis]

PROS N CONS

Let me start with the Pros:
- Very energy efficient just as heat pumps are designed to be. My lights are 600W with each strip emitting heat at ~39C and there is currently 18 strips of LEDs. It has been awesome at holding the temperature in the tent to within acceptable limits of 22C to 28C.
- Quiet. It’s surprisingly quiet.
- the size works for my garden size of 4’x8’ with only 4 plants (Canadian legal limit). I have the space inside my tent to hove the AC unit in there, but it can also be reconfigured to have the unit outside the tent, and use the vent ducts on the front side of the unit running in/out of the tent. Same benefit as my setup, just moving the vent ducts.
- dehumidifies the air as it cools it. *SEE ALSO: CONS*
- water condensation helps replenish the bucket for the fog emitter.

Cons:
- dehumidifies the air as it cools it. I don’t know yet how much it will try to dry the air as the plants get bigger. This is making it a challenge to get my VPD into a good range.
- it advertises that it shuts down when temp is reached, but mine hasn’t shut down fully even when the set temp is reached. It keeps running at a very low power level instead of just turning off.
- heavy as hell. Don’t think about putting this on a flimsy plastic table.
- the external air side exhaust vent gets very very hot. I had to cover it with insulation so it would stop radiating heat back into the space it is trying to cool.

Unknowns:
- We haven’t had much for warm temps here, so my grow room ambient temps have been between 5C at night and 15C during the day. Once the weather warms up and the ambient temp in the room gets over 25C, i don’t know how well the AC will do its job so stay tuned for that. If it struggles, then I’ll have to add an AC to the room to control the ambient temp and ease the stress on the tent space AC.
- Humidity…will i ever get my RH and temp to align? Currently it’s at 22-24C and a RH of 53%. I want my RH to be between 60-75% and haven’t been able to get there yet.

[YYCannabis]

Trying to get to a closed loop system, i am stuck at a cross roads for dealing with odor and excessive heat/humidity crisis situations.

I have my carbon filter scrubber setup venting outside. Since there isn’t much stank from the girls yet, I haven’t had to start air scrubbing. Usually, my air scrubber is triggered to come on at either excessive tent over-temperature control or too high RH control.

If i close loop the scrubber, then i lose the ability to deal with environment issues in the tent if that AC unit fails unless i buy another exhaust fan and charcoal scrubber. Stay tuned…i might have to go shopping LOL.