Humidity

I'm doing a cocoa grow and a 3X3.
There are four plants in 7 gallon fabric pots.
I have a 4-in exhaust fan that I just took the carbon filter off of (25% CFM).
Before that adjustment even running 2D humidifiers I can't get the RH under 60%.
I should only need 144ish CFM and I've got 148.5.

What I'm going to try next is a 6 in exhaust fan and use my 4-in as an intake fan.

The long room has a relative humidity of 40 to 55%
The grow tent at night gets over 70% RH without the dehumidifiers. I first tried a dehumidifier the capacity of 400 ml per day which didn't work I then purchased a dehumidifier with a capacity of 1,000 ml per day which also didn't work and I'm trying both with the above results.

Any tips or tricks?

Lung room*

Problem solved. New humidifier 22 pint humidifier

zlatson13 said:

Problem solved. New humidifier 22 pint humidifier

Click to expand...

That was going to be my recommendation. Glad you got it figured out

I'm having the same problem in my new set up.

Almost at chop and have no rh issues. My 2x4 is a shorty at 5’ tall so all that much less space. Very dense canopy and rh stays around 35-47%.

All my tents in the grow room are good. Exaust outside for the win. Draw in fresh air through door vent. 400w dehuey outside tents always on. 40rh in lung room.

Ambient temps, rh could be 75F 80rh and my room will be like 75F 40rh and similar in tents sometimes 80F in the brighter lit tents. 65F at night in tents yet no swings in rh.

Just realized dehueys arent made to last these days so keeping that in mind. If it goes out it will be bad so buying a backup and of a good brand is good idea.

I ran out of space and am ordering a 5x5 wondering if a 4" intake would be enough for that space

zlatson13 said:

I ran out of space and am ordering a 5x5 wondering if a 4" intake would be enough for that space

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Well it depends if you are going to match that 5x5 with a light for a 5x5 and thus more wattage and heat to remove.
Or if your just going to stick to your existing light and 3x3 footprint

For now a 3x3 light, I plan to keep them on one side and the humidifier on the other side. I didn't mention but there will be a 6" exhaust fan, just is the 4" intake big enough?

I don’t think you need an intake fan. I have an 8’ x 8’ room and use a 6” exhaust fan and a 7” passive intake. The passive intake needs to be slightly larger than the exhaust. The passive intake should be small enough to create a little negative pressure but large enough to not suck in your tent walls. My room is solid so no walls to suck in, but you should be able to make it work.

I used a passive intake for years,adding an intake fan was a game changer for my tent environments. I put them on a seperate controller so they only kick on when the rh is over 48. My temps stay around 84 in 4x8 tents with over 1000w in each tent

Well it's all set up. Check out the sap containing anthocyanins.

Key is having ur room in proper vpd zone and also know for humidity spikes are def at certain times of cycle and from night and day .

know vpd?

do u have a enviromental monitors ? I suggest having one , it’s a life savers ans paid for itself multi times for me in first round having it (pulse). From temps to light intensity to vpd and many things. Key is knowing and also being alerted if not in desired zones. Intill I had this I was def blind to some things but also def not aware of some instability. prevention is key and also knowing the issues exp for environmental desires.

I do have the vivosun control hub.