Very dry air - should I put humidifier in 4x4 tent?

[UberNuggets]

I have a 4x4 tent with not very much in it at all yet, about a dozen seedlings right now, hopefully more soon. I've noticed that the top layer of soil seems to get very dry in short time. I have 2 fans running in there at the moment. One is pointing at my light (250w MH in a cheap open-air reflector I rigged up), the 2nd is a 130cfm 6" inline fan blowing air out of the top of the tent.

Humidity inside the tent has been between 30-40% (temps in the high 70s... I usually run my thermostat in the house around 75). Outside of the tent in the bedroom in which it is located the humidity is around 45-50% thanks to a "humidifier" I rigged up with a box fan sitting atop a 30 gallon trash can filled halfway with water and a 150gph waterpump I had lying around is running in the bottom to get the surface of the water to froth up.

Would it make sense during these winter months with central heating on to put a small humidifier in the tent, or would this raise too many concerns for mold/mildew? There is a lot of airflow through the tent with everything closed up and the 6" inline fan running, which seems to be drying up my soil.

 

[messn'n'gommin']

I'm not very well versed in soil, I run Hempy buckets and they dry out quick! But, those numbers don't sound all that bad. As long as it stays below 60%, I wouldn't worry too much. Hopefully someone with more experience with soil can correct any errors in my thinking.

hth

 

[mg75]

from my experience:
if you constantly extract air from the tent, the humidifier is not going to work. you will have to have your extraction fan on a timer along with the humidifier. When one is on, the other is off and vice versa. Remember MH bulbs produce a lot of dry heat.
I have 2 humidifiers in my bloom room pointing exactly on the plants (it gets down to 20% in the winter). My veg room gets a smaller humidifier on a timer. The ones from Home Depot are good enough in my book.
Oh... I never run them when the lights are out!

 

[intotheunknown]

in a 4x4 tent a humidifier will work just fine to bump up some humidity
even when youre constantly venting...(at lower speeds) at full go on the fan will reduce the amount of overall humidity being added but will still help slightly depending on the locations of your intakes, and exhaust location, etc. however, its overall pointless.

i would recommend a fan speed controller to reduce the amount of air youre removing. and a timer for your humidifier.

pay close attention to what its adding, how fast its adding and what it takes to maintain the RH you want, and base your timing on temps/RH/fan speed etc.

being able to tweek all the variables will help you get it dialed in just right.

 

[farmari]

Better to have the humidifier in the room instead of the tent as the heat from the humidifier will raise the tent temperature and thus lower the relative humidity of the tent.
But I'm operating on the assumption that the tent is taking in air and exhausting into the room, while the room is closed. And that the room has air intakes/exhuast built in to the central heating system. Or is the setup different?

 

[Cann]

30-40% humidity is no problem...sometimes mine gets down to 20% and below - I don't sweat it. I'd rather have dry conditions than humid ones where I have to worry about mildew. Just remember that in low humidity conditions your plants will use a whole lot of K and Ca, so you will often get deficiencies if you do not supplement often with a little K and Ca (K and Ca can only be uptaken slowly, so feeding a lot at once won't be any faster)