First Post for me. I am 3 weeks into my second grow - 3 AK47 autos. Trying to get my humidity under control.
My setup:
2’x4’ Vivosun tent
AC Infinity 4" inline exhaust fan through carbon filter with CTR69P controller
AC Infinity internal clip on fan (single fan set on 3 out of 10, via the CTR69P above, and clipped to blow just above the top of the plants)
Inkbird humidity controller with humidifier set to blow into tent and small dehumidifier inside tent
Exhale CO2 bag inside tent
Spider Farmer SF2000
My tent is in my basement, in a huge room that runs approx 64-68F (temp) year-round, but humidity can vary a lot. In April, RH was in the mid 40s. In the last week it has probably varied between the 53% to over 70%. Right now, in the room the tent is sitting in, it’s 67F and 65% humidity. I have my Inkbird set to control humidity inside the tent at 60%. It says it’s at 61.7%. I have exhaust fan set to turn on at 77F (which it never gets to) and 65% RH. The AC Infinity controller shows 70F and between 64% to 65%, which keeps turning the exhaust fan on. The dehumidifier can’t do it’s job if the exhaust fan is running all the time.
On my first grow, I left a small opening on each side of the tent, using the bottom screen vent on each side. I set the tent exhaust fan to come on if temp or humidity setting is exceeded. Humidity wasn’t a problem, as it was over the winter.
With this grow, I added a small room dehumidifier inside the tent because the ambient humidity is normally too high. I closed the small screened vents completely at the bottom of the tent and installed a short 4" diameter dryer vent through a lower access port on the bottom left side of the tent with a louvered closure. The exhaust fan has no issue opening the louvers.
With my new configuration for this grow, the tent is closed up, no ventilation or fresh air, if the dehumidifier keeps the humidity in range. Ambient humidity is too high much of the time, this time of year, especially when I get into flowering (very soon). The lack of fresh air doesn’t seem like a good idea, both for CO2 and does that increase the possibility of mold. I would be interested in thoughts and even suggestions on settings for the humidity for the Inkbird controlling the dehumidifier and the controller for the exhaust fan. Should I always keep the tent vented.
With the exhaust the CO2 is wasted… It’ll leak… Plenty of it in our air now.
I would dehumidify the “lung” room and humidify tent with inkbird controller blowing dry air in to dry the tent on the other side of inkbird of the humidifier. I also have a fan running with the humidifier… Extention cord into inkbird humidifier side to blow the humidity around better.
Unfortunately, i have always had issues with 4" exhaust… My ac infinity 2x4 has two 4 inch diameter intakes and one 6" from the top exhausting out.
Airflow is your friend for managing both temp and humidity. >50% is okay in veg, but once you get to flowering you will want your RH <50% to prevent mold.
The only other thing I would add is that there isn’t enough lighting for the CO2 to do any good. CO2 does no good unless you are running > 1,300 PPFD at the plant’s canopy and you can’t get there with an SF2000. CO2 also requires other very specific environmental conditions that the majority of hobby growers don’t have the budget or experience to replicate.
If I understand the situation correctly, it sounds like you don’t really have a lung room. The room (entire basement) the tent is in isn’t really climate controlled. Tarping off a corner large enough to disperse most of the tent heat (10x10 ish?), would create a better lung room that could be dehumidified as needed. Then the tent could exchange into the lung room with dried air, that could dissipate the heat more easily into the rest of the basement. Hope that made sense.
Thank you all for the quick responses. I had to look up to see what a lung room is. That makes sense. My basement is partially finished and somewhat temp/humidity controlled. All the space around the tent is being used as an office and home brewery space, so tarping off an area would be difficult. I could relocate the tent, but struggling with finding a good spot. Maybe I should dehumidify the whole room and treat it as a lung room. I was concerned about the lack of airflow, as well.
I appreciate the input on the CO2. The Exhale isn’t cheap and has to be replaced after 6 months. So, not needing it would be great!
OK guys. The more I thought about your suggestions, the more sense it made. I set the entire room up as a lung room. I already had a large dehumidifier. I pulled the Inkbird out of the tent to control the large unit for the room the tent is in. I can shut a door to close off half of the basement. I will get another Inkbird for winter when I need to add humidity inside the tent. The exhaust fan should now pull fresh dryer air into the tent all the time. We will see how this goes. Thanks so much for your responses.
I have a very similar setup to you albeit my tent is no longer in the basement, I have a drying tent down there (cooler temp) so similar overall objective of ensuring air exchange in the tent while also controlling humidity.
If your grow tent resides within another room, that room can be referred to as the “lung room” as the air that your tent “sucks in” (either because of a vacuum created by the exhaust fan expelling air from the tent, or an intake fan) will be the surrounding air.
So, its advantageous to try to control the surrounding environment similarly to how you control the environment within your grow tent.
I personally find this easier in veg when you want humid conditions inside the tent and the exhaust fan doens’t need to run 24/7 like is more common during flowering. In this scenario a small humidifier should have no problem keeping RH within the desired range during veg.
During flowering I find it more difficult since you want < 50% RH in the tent AND cooler temperatures AND running the exhaust fan more frequently (24/7 for me in flower). My last run I had my grow tent in my office and had to run both a dehumidifier and air conditioning unit to keep that room cool and dry enough so that the conditions inside the tent remained ideal with the exhaust fan running all the time (passive intake).
So I guess thats a really long winded way of saying, control the humidity and temperature in the room in which your grow tent resides (the “lung” room) to the best of your ability, which is slightly easier since you can use larger appliances than you’re able to use inside the small 2x4 tent where space is a precious.
Thanks John!. Yes, controlling the space around the tent really is the best way. The room with the tent is probably about 600 square feet, which would require a lot of energy to heat/cool, dehumidify or humidify, etc., depending on the season. That can require a lot of energy. Walling off a portion isn’t really practical. I was hoping to control the conditions in the tent only, but with the air exchanges, I don’t think there is a practical solution other than the lung room approach.
The big dehumidifier in the lung room is working well as the all of you have suggested. Thanks to all of you for the great input! I think this is the only way to go.
Not entirely correct. It depends on your DLI, daily light integral. Any DLI over 40 moles would require co2. The DLI is 64.8 moles when running at only 1000 ppfd on a 18 on, 6 off light cycle. ppfd is measured in micro moles per meter squared per second. To determine your DLI, multiply your ppfd by 60 seconds, then by 60 minutes, then by how many hours you are running your lights.
1000ppfdx60x60x18=64,800,000 Divide by 1 million to go from micro moles to moles and you get a DLI of 64.8, which requires co2, otherwise you are just wasting electricity. Dr Bruce Bugbee of Utah State University covers this on a youtube video.
I been growing for yearts humisdity isn’t your primary concern, weatering excvessessaries are your topic,I usedf to grow indo0ors and the humidity is aropund what it should be around 50%excess will cause mildew etc. I seen others doing this and this is what I see, my issue is for you to read about growing, growing is the easiest , drying &curingis your primary issue
I use VPD which helps properly set the temps and humidity to the ideal levels for cannibas as well as other plants during specific stages. I am not anal about it but use it as a guide. I use DLI to set my light amount per day.
My humidity is fine… Also been growing since the 80s-90s.
In flower, after the stretch, I reduce the humidity, a bit at a time… First to about 50-55…then after buds start forming it gets down to 45-50rh.
Air flow, and proper ventilation, plus keeping a clean grow area I have not had any mold nor mildew issues at all.
As far as drying and curing… All good as well… Maybe check my thread.
I ran into alot of problems concerning humidity ect. seen some put them in way too early and some just dried completeluy out, the growing is nothing to it. I just harvested 5 plants which will last a long time, with hardley any maintenance, is all I can say about it, back in the 90s I had a walk in no humidity reader nothing just the plants and water, grew perfectly well, but when it came to drying them is tricky, too late or too soon, you have the humidity just right or otherwise turn to hay and that is what you will be smelling, I put my 2 cents in saying the drying & curing is the hardest part, I tried a lot of my plants trial & error ect. even crossbred
@Master-Grower Same… Used to grow in a long closet using Mh and HPS lights and a Dan growing primative homegrown hydro setup… Growing is definitely…imho…easier now with the meters, and charts for dli and vpd… Annnnd the internet.
If you’re an export, why are you asking qiuestions? All I’m going by experrience, ALL I SAID AND YOU FOUL MME? WHO ARE YOU TO QUESTION MY WORK? I have mmore experience, I never needed this I had live growers back long beore internet
I never asked but you did & told you your issues, TBH , asking questionds watering which I seen your work & not impressed, I’m being honest
