RH up, temp down struggle

Hey everyone.
Reaching out as I’m having a bit of an issue keeping my humidity up now that I have an exhaust to outside and a fresh air in.
I have a humidfior inside the tent set to high and the plants are just baby’s right now so I know it will be easier when they get larger (2x4 with 4 plants until new tent/light show up in about 20 days)

I’m in Canada so the air is dry and cold in the winter.
I have installed a window vent with 6" intake and 6" exhaust. The room it’s in is not sealed but it’s also not heated by the house furnace, has a baseboard as its an attachment with a sliding barn door.
So I set the baseboard to 18 (so plants ideally don’t get to cold and die) along with I haven’t ran vent hose from my intake right into the tent instead it just runs into the room so it warms up a bit and then gets sucked into the tent.
Temps are great with a low of 17/18 and a high of 21 as my exhaust (to outside the house) is running on its lowest setting.
I can’t seem to keep the humidity up though, I assume that the exhaust is just sucking my humidity outside. Temps are low, I could let them climb a little. so I’m thinking that if there is a controller out there that monitors both humidity and temp kicking my exhaust on when one or the other gets to high would be ideal to fix said issue currently…no?

As the winter progresses it’s going to get alot colder we are just hitting below freezing at night now so that’s why I don’t really think plumming the intake right into the tent is a good idea, I need some way to raise my intake temp before it hits the tent not sure how this is going to work all winter but giving it a go and open to suggestions.
My new tent I’m looking at outfitting with an AC infinity that monitors both humidity and temp.

I found a controller for my old fan but it’s half the price of the infinity… So does anyone have any better links or ideas? Otherwise I’m thinking about just pulling the old fan out and replacing it with an AC infinity. Only down side is I know it’s going to be next to impossible to sell the old duct fan

Inkbird has a dual controller (humidity and temp) or they have separate controllers if you just need one or the other


Yeah I seen them but they are half the cost of an AC infinity fan… 100$ in Canada and a 6inch fans 200$…

The single controllers are half of that one. You could just run the temp controller and have your fan kick on when it reaches a certain temp. Maybe I’m misunderstanding, are you also using the exhaust fan to pull in warmer air like a passive intake?


Correct,currently the exhaust fan is pulling the fresh air in from the room that is fresh yet cool.
I also have 2 small clip fans inside one of Wich sorta assists with intake.

Temp is currently what would kick the fan on but as the grow goes on and the Temps get colder I feel like humidity will be what I want the fan to kick in…
That’s why I don’t want to get just a single controller :sob:

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Why don’t you dome them while fairly small and once the canopy develops into your space the RH will inevitably go up anyway.

I run an exhaust fan (6") tied to a thermostat located strategically in the grow space. This allows the inside RH to climb along with the temp and the fan exhausts, exchanging air, lowering temps and RH. But the fan only runs for a minute or two; no issues with the plants. So; there may be some kind of exhaust management you could work with to help.

But I’d dome them right now, that’s easy-peasy.


I have the domes but I removed them because i remember @dbrn32 talking about things blocking light so I figured that cheap plastic is blocking the light, I have large domes and my CFL’s would not get the light to them like they need to grow…

Now of course in the new tent I’ll have a 3500k led and not my current 3000k led so it will be able to veg much better.

I appreciate all the good ideas don’t mean to shoot them down =(
See kids this is why you pay for the right equipment the first time! Haha
This struggle just makes me so much more excited for when I get my new tent setup I’m sure I’ll want to just get rid of this old one but hard to sell used grow gear.

You have more than enough light, and you can lower if you need more intensity. The rh will help you more right now.

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That’s my feeling too. (BTW: I do my whole grow in 3,000K and it does just fine)

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I’m using the CFL’s though not the QB, and the girlfriends home so she can’t switch it.
So it’s CFL’s farther away and RH up or its RH down and light closer…

Edit: she’s going to see if she can get 2 more domes as I currently only have 2, will place light right on top of dome should do for now. Fingers crossed they still have the domes in the store

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Clear Solo cup, top of a layer cake at the Grocery store (they might even sell you a couple). Restaurant supply houses like Smart 'n Final has stuff too. Or good old Amazon.


Dollar store had the one with the closable vents so Ill get her to stop there but those are all amazing ideas I would have never thought of, I tried a 2L but it wasn’t wide enough for very long.
Haha yeah ask the girlfriend to buy me 2 cheese cheese cakes so I can have the kids :joy::roll_eyes: oh she’s gonna love me

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Hi, I just bought the 6" AC Infinty to replace a hi volume 4 ". The controller will be best suited for either heat or humidity but probably not both. The reason is that if the temp is good but RH is high it will vent your temp. Conversely, if the temp is hi and RH is good it will vent you RH too. So I run an Inkbird too to run one or the other independently. The Inkbird has 2 work outputs and the AC infinity can be connected to it and be turned on and off without depending on the fan controller also, which some guys do too. That way if you have a bit too much heat you can have supplemental RH turn on and off independently from the heat venting and ■■■■ versa.

I don’t fully get this because I’m about to crash I will read it over and try to understand better in the am. I will say though I feel like I only need to control one at a time, it’s just I need to control RH early on and temp later on but we will see.
By supplementary you mean a humidfior?
And if so how because my humidfior shuts off if the power goes off and it need you to click the hard button even if it gets power turned back on.

I remember us all talking about how cool mist humidfiors wreck carbon filters unless your using $$ distilled water so I don’t run a cool mist one just some cheap I picked up at a 2nd hand store.

That being said I just want to announce I just placed the order for my new setup, so my 1600$CAD setup is on its way unfortunately it gonna take about 2 weeks for some parts to show up and that means it will be 3 weeks before I get my hands to set it all up (work scedule)

Night all

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Goodnight Nicky,
To be honest, I find a humidifier is only needed in the early stages anyway, and then venting to control de humidity later. But! I find for me anyway because I use Fluence Spydr lights, it can be hard to stay warm because they run so cool! So I run supplemental heat in the winter off the Inkbird controller. I use the fan to replace air and to control humidity.

So let’s clarify this.
You have the fan with both sensors but also have a inkbird. The inkbird runs your heater though for temp and your fan is monitoring the RH yeah?

I will have to play with it once I get all my parts, but I will most likely be using the AC mostly for RH control as well considering I have the room temp monitored by a baseboard thermostat.
Having a separate room with fresh air into the room and heat control while venting oxygen rich hot air out is ideal.
I purposely bought more aluminum ducting because I think I can use it to help with my heating/cooling as well.
For example i may run my warm exhaust vent wrapped around my intake vent to help with heating the cool air that’s coming in. I haven’t run the intake hose yet as the plants are still so small I figure room airs doing fine and I’m not home till Thursday.

I’m wondering if I should get a little fan for the fresh air intake and run it on a timer, to force in fresh air into the room every once and a while (not sure of how often that would be but yea)

My new light will produce more heat and thus the baseboards will kick in less often, hoping to use the full length of the exhaust venting just to try and get every bit of heat back into the room before kicking the air outside.
Currently I have the flexible aluminum foil duct but maybe I should upgrade to the solid aluminum stuff as it would act more as a heatsink…

Sounds like a viable plan. You may want to try to avoid too many turns in the piping and the longer the run the more the resistance to flow. Although, the little AC Infinity 6" kicks out pretty good at full blast. The thing I don’t like about its controller is the settings are amazingly limited compared to the Inkbird. For instance, the Inkbird can not only be set to come on at say 80f it can also be programmed to run until it hits 75f or 73f same for RH. The AC does not have that facility. The spread is fixed and is not adjustable to my knowledge. Have fun though, I am, it’s a pretty cool learning curve.

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So I have my new tent with the AC infinity controller and now learned it can only control the fan off of one setting, so temp high, temp low, RH high, RH low, timer, full on, off… Sorta lame I expected more but still useful.
I think this combined with a humidity controller that would turn on/off humidifier during veg and dehumidifier in flower is the setup I will go for.
In turn I ordered the duel inkbird controller as well knowing it can do the same thing for my old tent but won’t control fan speed (I will have to manually adjust it)

Waiting on the controller and 2 new temp/humidity sensors as mine kicked the bucket.
Domes have helped for sure.

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I live in Interior Alaska. I feel your pain!

This year, I’ve been able to get my temps and rh to stay fairly steady. I put a space heater outside my tent and a humidifier in the tent. I keep the heater at 75F during lights off and the humidifier set to low or even off. The moment the lights come on, heater goes off and humidifier goes up to medium.

For a month, now, the temps/rh have stayed between 77-80F/65-66%. In past grows, I struggled with night time humidity of 85%+!

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One tent has the AC infinity and domes, no humidifier right now, I don’t have a humidfior controller or a 2nd humidifier.
While the other has a humidfior on high all the time and fan on lowest setting but the duel inkbird controller will go in that tent Wednesday.

So down the road I will get a humidfior controer for the new tent