I live in the north east. In the summer it gets up to 100 and in the winter down to -10.
My tent is in my bedroom. The only space for it.
In veg I sailed through setting any humidity I wanted. Well now I’m three weeks in flower and I’m struggling!!!
The first dehumidifier did 40 during the day at night 65. I thought that was high from what I heard. The next dehumidifier was aver 60s w spikes into the 70. The third one which came recommended from another grower (with a YouTube channel) ain’t doing shit either.
I have all my traps closed. As to not let light in during the dark period. I’ve recently (as of today ) switched to light out during day. Light on at night. Hopefully that helps. I have the Honeywell turbo fan blowing on the bottom. A small desk fan clipped to the pole and an exhaust fan with a carbon filter.
The tent is a 2x4x5 Theres only one plant ATM (this will be my flower tent and I will be putting one to two more plants tops.)
Got any ideas to help me out?
I’m looking at adding another intake fan. Usually I leave the traps open and set the fan I. The tent Infront of it so it will suck air in and blow it around the tent. But because I’m in flower I can’t have the trap open all the time.
Are these any good?
Are they only to add with another fan in the same pipe?
Or can I put this with it’s own pipe on the bottom of the tent? I’m thinking if I put an intake fan with long enough tubing. It’ll get more fresh air in. And the long piping will stop light penetration
Maybe I should buy an a/c infinity 6 inch exhaust fan. Then put what I have now blowing air in? With long enough piping to not allow light.
This is what I have now
@BassNBricks
I had the same issue when my plants went into flower mode. I had a small dehumidifier in the tent and didnt do much. I tried a big one outside the tent and eliminated the one inside the tent. It did do much better. Maybe try it in the room instead of the tent.
A phrase I often repeat is “I have suggestions, but not necessarily solutions”. So here they are.
If you look around online, you’ll find plenty of ideas on how to build light traps for the screened intake vents at the bottom of the tent. Usually out of common household items. A modified cardboard box will usually do.
Then crank up the exhaust and keep it running. Keep a dehumidifier running in the room the tent is in.
Relative Humidity is, well, relative. The warmer it is, the lower the relative humidity. Don’t get it hot, just don’t let it get too cool at night, or your humidity will rocket up.
Or just only grow in the dry, dry wintertime.
Good luck, the struggle is real!
I agree with @4204life, dehumidifiers in the tent are negated by proper air exchange rate. Dehumidifier in the lung room will go a long way in helping resolve the issue.
That’s what I was thinking! The overlooked lung room 
Dehumidifier in the tent doesn’t work so good.
At times I use two of these dehumidifiers set one to kick off around 5hrs and the other to come on at that time works nice while I’m at work when the light is off. I leave a bottom flap open so the the exhaust fan can pull air from the lung room. Never had a light leak issue.
Sounds like a solid plan growmie! And as @Bubbala points out, RH raises and lowers with air temp. Another cheap “fixit” for high humidity at night is to run a boot dryer in the tent. It pulls only 36w and the heat is gentle enough not to fry foliage yet robust enough to shave a few percentage points off the humidity level. I removed a portion of the pedestal and took the shoe horns off of the one I run.
@BassNBricks IMO AC Infinity is the benchmark standard in the exhaust fan industry. I use them along with their clip fans and highly recommend them. Their controllers are on point as well. 
My bed room air is already at 40 percent the dehumidifier isn’t getting it any lower then that. So putting it in the *lung room" still isn’t doing anything. I’m gonna search the Internet for light blocking those bottom vents.
@BassNBricks Yeah, dehumidifiers work pretty good dropping levels if they’re high, but if you’re already down to 40%, their effectiveness really drops off. That’s pretty consistent with what I’ve found too.
@SeaOhAreWhy Have you used the 6" oscillating fans from AC? Being impressed with my AC exhaust, I was really intrigued by them, but many of the reviews state that the oscillation part fails on them quite often. Any experience with that?
Do you have a closet in your bedroom? I removed the bifold closet doors and got a curtain rod and blackout curtains and put my 2x4x6 tent inside. I leave the bottom air hole open with a small fan outside the opening (basically fits the hole) and the one top hole open also. When it’s lights out I close up curtains in that bedroom. I’m also having humidity issues inside my tent( just flipped to 12/12 1 week ago) I have a dehumidifier in the bedroom that helps a little, and I’ve been unzipping the top of the tent door during lights on and that helps drop it some more. I’ve got a few weeks to get it figured out better , I’ll let you know if I come up with anything.
I use their oscillating fans as well but only use the oscillator during flower. I think if you were to run it 24/7, it would fail inevitably.
Lowering the humidity in the bedroom won’t accomplish anything if you’re not constantly exchanging air between the bedroom and the tent. You need the lower vents open and your exhaust fan running.
This is the primary reason I initially switched to autos. I got tired of fighting between blackout darkness and moving enough CFM’s to keep everything else in check. It was a good move, for me anyway, because now I love autos and couldn’t care less about minor light leaks.
@Cap_Ron I’m gonna have to try autos. Just once atleast. I love LST. And getting good at it… I think.
I’m sending back the dehumidifier and I’m buying a second exhaust/intake fan. I’m gonna run a 6" up top and a 4inch on the bottom the piping and the mesh covers I see should hold the light out. Also gonna get an oscillating stand up fan.
Just an FYI, not saying a 2nd fan is a bad idea, but I’ve always just run a single exhaust fan, properly sized of course. As long as you’re providing an adequate path for passive intake, the air the exhaust fan pushes out will draw your return air in. Perhaps consider using that 2nd fan money for something else as long as your current exhaust fan can move enough CFM’s for your tent size.
No problem training autos. This is a Fruit by the Foot auto, and today is day 42. I was late topping her, you’ll see it was above the 5th node. Normally I’d go above the 4th, but I let her go a bit far and didn’t want to cut that much off. She seemed to have taken to it just fine!
Front view
And from the top
This stuff might be helpful for you as well. It’s not totally light blocking, but doubled it does pretty good.
I use it in a bunch of ways.
I get it in 24x36 sheets in Home Depot.
Well technically it would only be one exhaust fan. The other fan would just be an intake. Instead of a passive one. However I will try this filters over the ports to block light before adding a direct intake fan.
Ron is trying to put you on the right path. Fans in-line fight each-other. You would get more flow running those two fans in parallel (side-by-side) as exhaust fans, & giving them enough intake area to do so. But really what you should do at that point is go to a 6" centrifugal or hybrid exhaust fan & give it enough intake area so it can reach its max flow. The 4" exhaust fan by itself isn’t enough for that sized tent, even if you set it up for max flow, but a proper 6" with enough intake area should be enough for that tent. So the move would be to go to a single 6" exhaust fan, & give it enough intake area to reach max flow. You might have to open up or add more intake area if using light traps, since they usually steal flow, depending on how you do it. Jardin makes some flanges with light trap inserts, but they are kind of pricey at around $30+ each last time I looked. You can DIY traps no problem.
Also those short carbon filters steal a lot of flow on the outbound side of the fan. Longer ones, or larger ones (step-up connector to go from 6" fan to 8" filter for example) can flow better. I bench-flowed a short 4" carbon filter on a cheap Vivosun 4" centrifugal fan, & it lost 60% of its flow from the filter alone.