Need help regarding badly high humidity again

[UKgrower320]

So I made a post a while back on my humidity being to high, got told to use cat liter or a dihumidifier

Well I've used both an it's still in the 80s tent closed, 65% tent open...

I'm two weeks into flower and basically ripping my hair out in case of bid rot, something I genuinely can not be bothered with because I rely on this crop to come of these crappy antidepressants.

I use a 250W HPS (sometimes run a 300W CFL but thats vegging my next set of plants)

4inch fan, duct and filter.

6 inch clip fan

In a 80x80x160cm grow tent.

Ive been told to go up to a 6 or 5 inch fan but basically been told by a hydro shop its point less.

I'm just waiting to see what people say before I return the dehumidifier.

My vent tent doesn't have this problem what so ever and thats a 60x60x140cm basically running the same stuff in it, the 4 plants ive got in the 80x160cm are far to big to even think about putting them in, they are nearly about 25cm away from the HPS.

 

[Backlipslide]

Ok so you need to up your ventilation on the inside of the tent, and/or have another fan inside moving more air around. When you close the door, do you see a negative pressure on the inside of the tent? Do you see the door vacuum seal shut. What kind of air extraction do you have?

 

[Greenlizard]

Is the dehumidifier inside the tent?
Do you have a fresh air intake?
Most people just let the extraction fan suck against the negative pressure of the tent but I allow a piece of flexible ducting to pass through one of the lower ports of my tent with a couple S turns in it so no light can leak back into it. The tent still compresses with the negative pressure but fresh air is being drawn in at a much higher rate and the extraction fan isn't up against so much resistance. Works well for me...

 

[SmokingWings]

I am of the belief that your humidity problem starts with the plants themselves. They are transpiring water through their leaves and from whatever you are growing the plants in. The cabinet that I flower the plants in does the same thing for the night and day after a thorough watering. Within 24 hours it drops down to whatever the humidity in the room is.

One possibility is to leave the tent open while the lights are on and use the dehumidifier to drop the level in room. That is something along the lines of what Greenlizard is saying in the above msg. Not sure if that would work if you are growing in a hydroponic set-up since I do not know how much water evaporates off of that type of system.

Hopefully you can find something that helps. Have a good day.

 

[DaddyKush]

Basically a dehumidifier is going to be your best solution. You can also use your exhaust fan to suck the humidity out of the room but your solution will revolve around the dehumidifier. What I'd try is run the dehumidifier as necessary, keep the tent door open a bit during lights on, and then run the exhaust fan during lights out. That should keep things at a manageable level.

 

[LiberalThinker]

Is the dehumidifier inside the tent?
Do you have a fresh air intake?
Most people just let the extraction fan suck against the negative pressure of the tent but I allow a piece of flexible ducting to pass through one of the lower ports of my tent with a couple S turns in it so no light can leak back into it. The tent still compresses with the negative pressure but fresh air is being drawn in at a much higher rate and the extraction fan isn't up against so much resistance. Works well for me...

I do this too and get the same result.

 

[Bush Doctor 77]

With the average ambient humidity so high where you live, you have a problem. If your outside air is 65% humidity, and you are drawing a lot of air into your grow area, you are starting at 65%. You could isolate your whole area from outside air, but then you probably need CO2. Your best option may be larger exhaust. Herb can grow in very high humidity if there is a lot of moving fresh air on the leaf surfaces. Think Jamaica, Thailand, Vietnam etc. where the air is often saturated.

 

[Weaselcracker]

Lots of good solutions here. I’m in the same situation as far as high humidity outside - almost always between 80 -100%. During lights on the heat from your light should solve the issue. During lights off run a small dehum. Always keep movement fans running. Another one or two of your clip-on fans would be good.

The fact that your rh drops with the tent open shows you just need more ventilation.

Stop pulling your hair out- you won’t get budrot at two weeks flowering, as long as you have movement fans. You have till late flowering to solve the problem.