6" inline for 2x4?

I'm having a hard time controlling my humidity at night in my new 2x4 set up. Running AC Infinity 4" at almost full blast and cant get my humidity under 55%. Is anyone running a 6" in their 2x4? Would it be worth the upgrade?

It seems unlikely that simply adding more cfm would help much. Lowering the humidity, if possible, would be a better option.

Is a dehumidifier feasible?

I've always considered anything less than 60% RH fine during lights out but ymmv.

Add some heat if the temps aren’t too high already. That will help the humidity lower.
There’s more than one way to skin this kitty.
Dehu?
vent outside?

If humidity in the source air is lower then yes a greater air exchange will lower it in the tent.
If it's not, it won't.

But itl also drop your temps.

As a last resort a defoliation can help, less leaves, less transpiration, but only on big plants.

But in all honesty, I'd be OK with 55%

I'm not actually too worried about it at this point (just a week into flower) but I could see in a few weeks as the weather turns warmer it might become an issue. I'm just a little bummed that the fan is running on 8 of 10 right now (at night) and not capable of getting closer to the ambient room RH which is around 35%. Seems like I'm not going to get the headroom I thought I would and running at full blast isn't going to be ideal. Figured maybe a 6" would allow me to have a little more control.

Well in those circumstances a 6" would improve matters, assuming you're venting outside and not just building up humidity in the room itself

Your room is avg 35% but you can't get it lower than 55% ?
Sounds not logical...
2x4 is small... even a 100 cfm vent should make rh levels inside the tent somewhat equal.
To me it sounds like your RH sensor is just showing you a single spot rh measurement which is probably not your avg rh inside the tent.
Or maybe you just put a shitload of big plants in there which is not plausible so much..
Other than that maybe adjust temps to be more in the 26-28c range throughout, it will help some.

Is your intake sufficient to let your current fan move the air? I assume it is, but just wanted to toss that out as I have seen folks struggle when the intake was not sized large enough to let the fan "Breathe" and it was just working like hell and not really moving much air.

Hope you get it figured out!

I've got a 2x2.5 with a 4inch that turns full blast and barely keeps it below 50% humidity. But it's only when the temperature drops below 69/70f. I've kinda come to the conclusion that unless I raise the temperature I can't drop the rh anymore.

UnknownRemedy said:

I've got a 2x2.5 with a 4inch that turns full blast and barely keeps it below 50% humidity. But it's only when the temperature drops below 69/70f. I've kinda come to the conclusion that unless I raise the temperature I can't drop the rh anymore.

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Interesting. Thats pretty much the problem I'm having. Lights on is fine. 77F with 55% RH (VPD around 1.19). At 30 minutes after lights out temps drop to 67 and RH jumps to 62% (VPD of .72) and fan is blasting at 10/10. Its in a small room about 7x7 with shitty insulation but I keep the door open and the general humidity in the house has been 30 to 35%. I don't get it. I've only got 3 plants in there about 24" each and still stretching. I really think this may be a problem as the weather gets warmer and more humid. I'm going to toss a tower fan in the room and see if I can push some of the humid air out of the "lung" room.

Rivendell said:

Is your intake sufficient to let your current fan move the air? I assume it is, but just wanted to toss that out as I have seen folks struggle when the intake was not sized large enough to let the fan "Breathe" and it was just working like hell and not really moving much air.

Hope you get it figured out!

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I've got both bottom flaps to the tent wide open and should be pulling in plenty of fresh air from the bottom of the tent and out through the hose which is prox 2/3 high in the tent.. About 24 inches above the canopy.

coreywebster said:

Well in those circumstances a 6" would improve matters, assuming you're venting outside and not just building up humidity in the room itself

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Its a tiny room. So its possible humidity is building up in that room. Although I keep the door open and I wouldn't think that would be a problem. Ill look into it. I just put a humidistat in the room. I'll check back in with the info in a bit.

pegboy said:

Interesting. Thats pretty much the problem I'm having. Lights on is fine. 77F with 55% RH (VPD around 1.19). At 30 minutes after lights out temps drop to 67 and RH jumps to 62% (VPD of .72) and fan is blasting at 10/10. Its in a small room about 7x7 with shitty insulation but I keep the door open and the general humidity in the house has been 30 to 35%. I don't get it. I've only got 3 plants in there about 24" each and still stretching. I really think this may be a problem as the weather gets warmer and more humid. I'm going to toss a tower fan in the room and see if I can push some of the humid air out of the "lung" room.

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Honestly I wouldn't worry about it. When my tent gets warmer it stops struggling to remove the humidity. When my tent makes it up to 69/70f it only takes my fan maybe 10 minutes to raise the vpd to 1.5.

Edit: Wait only 1.19 with lights on? How far away is the exhaust? How many plants? Are the plants big? I only grow one plant in a 2x2, and if I had a 2x4 I'd personally only grow 2 plants.

RH right now in the room is 50%. RH in tent with fan on full blast is 62%. With lights out that is.

EDIT: Also RH in my 2x2 tent (currently no plants) in the next room maybe 20 feet away is at 40% RH.

I don't quite have an answer for you but like today my tent is at 71 with lights off and she has no problem dealing with the rh at half speed.

pegboy said:

I've got both bottom flaps to the tent wide open and should be pulling in plenty of fresh air from the bottom of the tent and out through the hose which is prox 2/3 high in the tent.. About 24 inches above the canopy.

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Wait wait, you don't have an exhaust vent from the tent to the outside/room ?
Just holes ? If so no wonder your RH don't drop, moving the air inside the space won't do nothing, you need to extract the inner tent air (outside the room preferably) or into the room itself where other air movement will deal with the added rh.
Create 2 air directions at your house/location first so air can move freely and reach your tent, add a vent to the upper hole with a hose to the window or just the room.

Are you not allowing proper dry back between watering? What kind of pots are you using?

pegboy said:

Its a tiny room. So its possible humidity is building up in that room. Although I keep the door open and I wouldn't think that would be a problem. Ill look into it. I just put a humidistat in the room. I'll check back in with the info in a bit.

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I'm in the same situation... You need to get humidity out of the room. Maybe one or more fans outside the door to move humid air away? Or run the exhaust duct to/out the door, possibly down a hallway? I ran my exhaust to the rooms cold air return. It helped, but I still need a dehu at times, and I only grow in winter. I could exhaust out the window, but why blow warm air outside during winter?

I think you need a dehu, most indoors do. To operate with an external controller (Inkbird, AC Infinity etc.), get one that can be controlled by switching the power on/off, most new ones have a power button that must be pressed. I bought two old ones off Craigs list, no power buttons and they will be running long after a new one has died. The old ones are less efficient though.

When I grew in my cloakroom butchered the door haha top was my excaust vent bottom intake was ducted bit a silk screen on it keep dust and all out
Used to put my hand at the bottom was cold air getting sucked in
Worked a treat

pegboy said:

I'm having a hard time controlling my humidity at night in my new 2x4 set up. Running AC Infinity 4" at almost full blast and cant get my humidity under 55%. Is anyone running a 6" in their 2x4? Would it be worth the upgrade?

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-passive intake, be sure intake is around 3x the area of the exhaust fan. That would be two 6" passive intakes for a 4" exhaust (200 cfm ac infinity)
-Note: if adding a filter/ screen the exhaust will no longer push the 200 CFM it is advertised to. This goes for the intake holes as well-- if adding a screen to filter the intake it is good to increase the hole depending how fine the screen is to make up for the loss. I think you could probably get away with a second 4" fan used as an intake, which is how I like to set up (active intake + active exhaust), I use an intake filter as well.
-Use hard ducting to make it work most efficient. This will also make it louder though. Long sweep bends are better than short sweeps
-set up the exhaust fan up high, and the intake down low (humidity rises as well as heat)
- reduce evaporation from drain tray, pots, and reservoir if possible by capping
-thinning the foliage can help
-Make sure your hygrometer isn't effected by your lights and is giving an accurate reading