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.

[golfnrl]

Welcome back. That grow space is awesome. I'd love to have the space around my place for something like that. thanks for sharing the upgrade info. I'm considering one of those split units for my outdoor kitchen. Looks like to me the portable AC allows you to create a lung room for growing wherever its needed or wanted and that is a very cool thing. My grow tent is in a spare BR with its own HVAC zone. I fell into that one and did not know how good that really is. Over time I've figured out how to manage the temps and RH for my situation but it has been a journey. I am now using AC Infinity humidifiers for each of my grow tents, a 4x4 and a 2x4. I was skeptical about their ability to maintain any kind of consistency but after using them, I'm a believer. I have them attached to the ACI controller. The RH stays at whatever level I have set. That works well for the time of year in my location because I need to raise the RH. I'll need to lower it as summer approaches. The lung room AC handles that and lowers the RH in the tent. I've tried in-tent de-humidifiers and I haven't found one that worked. What are you using to raise the RH?

What are those blue hangers for? Drying? Maybe plant support?

[YYCannabis]

Hey golfnrl
Those blue hangers are for drying. I figure that the best place to keep them so they don’t tangle and break, is to keep them in the tent.
For raising the RH i have just one little ultrasonic device from Amazon.But it’s too small, so i need to get a larger one soon.

[Bluey]

I'm running two heat pump air-conditioning units in my flower room. It's 11x7foot, pretty well sealed, and I do 5 full size plants max that produced over a pound each of premium first rate bud and almost another pound each of lower grade bud for extracts. I run 2050W of full spectrum LED lighting with the canopy foot print about 10 x 5.Im not running a carbon filter to keep negative pressure inside the room and you can smell my dank from the public road. This is an issue I need to rectify.

I have high humidity where I live. I also run a 50ltrs/day dehumidifier that runs flat out 24/7 from mid flower onwards.

One AC stays on 24/7 once lights get to 100%, that's a 1.5kw cool wall unit that vents about 5% fresh air. I can drop that back to zero.

The other unit I operate on its own thermostat and its a 3.1kw cool unit that functions the same as yours. I have it set up to only exhaust the hot air which reduces its effectiveness as a dehumidifier and also draws in a bit more fresh air into the flower room from outside. It sits in the flower room.

So it's a bit of a compromise. As soon as you introduce AC you're lowering RH in the room. Setup the way you have it will lower it more but it substantially reduces air changeover....so I guess you just have to trial it and see how it works for you best.

[YYCannabis]

Update on the garden.

- so far, i have had a good enviro over the last month. Tent has held steady at 26C and 65%rH. This has kept my VPD in a happy range for 3 of the 4 plants.
- I DIY’d a stank buster tube (Bottom right corner of tent) to recycle the air and remove the smell, and I gotta say that it has been working wonders. Entering my lung room, there is no smell from the garden.
- Upgraded my ultrasonic fogger from the weak little single disk emitter to a larger 6 disk emitter, and what a difference. This unit can jack-up my tent from 35%rH to 65%rH in a matter of minutes.
- Discovered the “dehumidify” feature of the A/C is much better than just running the A/C in normal mode. Both modes will condense some water from the air as it cools it, but the dehumidify mode seems to condense and dry the air better with more consistency.
- I did have some minor equipment failures with air stones. I’ve never had a single air stone failure before this garden, and I had three recently. Fortunately i had spare stones as a backup.

Now on to the girls…
- The plant on the far right is Bubba White and she has been a pain in the ass since she went through her growth spurts. Weak flaccid limbs and stalk. You can see in the pic that I’m using some soft wraps to hold some of the mid-branches upwards towards the stalk…and I’m using a chunk of 2x4 with more soft wrap to hold the stalk upright. I tried all the tricks I know of to get her to build more osmotic pressure and “firm-up” before realizing that it’s a genetic issue. She is about 56 days into flower. Trichs on mid-branches are showing about 5% amber; top cola is around 10% amber; lowest branches and popcorns are practically 0% amber. She will be my “Couch-lock” plant with a target of +15% amber up top and hopefully around 10-15% amber in the mid-branches. Today I started the flush with her (fresh water, no nutes) and will keep her that way for the next 5-7 days until i chop her down. (Big win for the other 3 plants as they will be getting more light)

- next to Bubba White is my Donny Burger. What an absolute treat to grow. She has done nothing but drink and grow without any complaints. Very easy to grow. I’m planning to harvest her at between 5-10% amber for a good balanced effect.

- Next to Donny is Cake Crasher. She’s been finicky since she switched to flower. This one needed a small amount of grow nutes during the first 2.5 weeks of flowering as she didn’t really have that first growth spurt that would normally happen, and all her leaves were losing turgor and hanging like wet napkins. A mix of 2:1 Bloom:Grow got her leaves perked back up, but she missed that growth spurt. Aside from that, she has been a bushy little tree. But strangely, as seen in the pic of her cola, she is way far behind in trich production compared to the other 3 plants. Hoping to harvest her when she is approx 5% amber for a balanced effect that leans towards heady buzz.

- Last plant on the far left is White Widow (i love this strain, just not these seeds from Crop King Seeds). Interestingly, she also needed Grow nutes for the first few weeks of flower. And just like Cake Crasher, she didn’t really hit that first stretch. Never had droopy leaves, but is way shorter than she should be (in past grows WW usually hits 32-36” tall). But to be fair, she does have a crippled stalk from the time she was seedling. That was my fault. As for harvest, I plan on this one being my pick-me-up plant and will harvest her when mid-branch buds are all milky with very little amber. (In my personal opinion, there is no better buzz than a heady White Widow buzz).

[ductwizard]

that is a thing of beauty, i'll be a happy sob if my w.w. turns out 1/2 that good

[YYCannabis]

WW is very easy to grow and tolerant of grower mistakes. For example, this very plant fell limp…like, dead flat on the pebbles limp, when she only had one set of true leaves. I managed to prop her up with toothpicks and elastics until her stalk started to get fibrous. But i took away her supports too soon and now she has a terrible bend at the base.
All of these plants are from Crop King Seeds. I don’t think I’ll buy from them again. I’m estimating that this WW will yield about 8oz, whereas my last couple of gardens had WWs that produced 15-17oz each. Those were real banger plants from Greenhouse Seeds, but I cant get them in canada anymore

To get the best out of these plants means you have to put time and attention into them. Anybody can grow “weed”, but only an attentive gardener can grow top-shelf bud, and WW rewards the gardener well

[ductwizard]

my ww's are outside and started slow but after a week of sun put on a lot of bushiness, they're in good composted soil in 5 gal. pails. i'd be happy with 8 oz. per plant. free seeds in a trade with the owner of justcannabisseeds.com

[Bluey]

Oh lovely, really nice. Shit that plant on the right did take off on you hey.

I'm a little surprised your showing such great frost with 65% RH. Very surprised.

Great job and nice diversity of strains. You've done really well with all that diversity together.

[YYCannabis]

VPD in the correct range encourages trich emergence. If the plants are able to breathe freely, it aids in the ability to squeeze out sticky-ickies like crazy.
Yeah…that Bubba plant put my DIY light design to the test. I wanted to get a blend of strains that were all high THC content, but all have different main effects.