Light Change Decreases Humidity in Tent

[WizardsNThings]

Just switched a cheaper 500W LED for a Vipaspectra 450W (clearly much better quality). The temperature within an hour went up about 8 to 10 degrees (to 80F), and the humidity dropped from high 40s to 27. I turned up my exhaust to suck out the hot air which dropped the temp down to 72 or so, but humidity is staying put. I added some wet towels for now until I figure this out. Increasing temp, sure, I get that. Does it make sense that a stronger light pulling more power decreases the humidity in the tent somehow?

2 x 4 x 5 grow tent
4" inline fan w/ carbon filter (passive air intake)
Fan in tent for airflow
1 x 450W Vipaspectra LED
1x 500W LED

[Potted]

Heat evaporates moisture? Doesn’t it? and sends it out the exaust. Imo

[WizardsNThings]

Yeeah it does. Hmm, maybe need to add a humidifier then

[Guest]

I grow in a room thats 12ft by 12ft. Never had a tent so im just guessing.
radiant heat, such as a light , is a dry heat. I remember getting nose bleeds from those old radiator heaters in my homeplace. Lol

A small humidifier may be the long term solution. But you got a great light now its gonna be worth it.

Food for thought on these posts ... Im learning alot here at gwe

[WizardsNThings]

Agreed. The quality is much, much better. A small humidifier should suffice. Love this forum, only started posting last week but have used the site for all my info. It really is amazing

[Toker1]

Heat has the ability to vaporize the moisture in the air. Higher temps allow more moisture to be held in the air. So when ambient moisture content in the air doesn’t change...adding heat will lower RH.
What is the ambient RH like in the room your tent sits in?

[WizardsNThings]

Low 20s.

[Toker1]

So even if you humidify the tent... with the exhaust you will not be able to raise RH than much.
Best to raise RH inside the room the tent sits in. Let the exhaust pull in moist air from the outside.
Look into a portable swamp cooler for this application... you can attach a garden hose and set it up on a humidity switch for automatic control.

[WizardsNThings]

I got a 1.2 gallon dehumidifier from Wal-Mart and put it about 5ft from the intake to increase RH in the room and tent. The tent is now up around 45-50% so it seems to have worked fairly well.

[WizardsNThings]

So I chopped one plant using the cheaper 500W light, and turned it off. The temperature/humidity was now able to be maintained at a good level without the exhaust full bore to keep the temp down. I still need the humidifier. I've since chopped my 2nd plant as well but am looking ahead to my next grow. I'd like to replace the 500W with another 450W Vipaspectra but then I will definitely have a humidity issue. Assuming I get a swamp cooler, or grow in the summer when it's more humid, I think I will need to step up to a 6" exhaust fan to vent the hot air put off by the 2 more robust lights. My long winded question is, can I use a 6" exhaust fan with my 4" carbon filter if I get an adapter, or will this be more inefficient than replacing both?

[Toker1]

Trying to pull the cfm of a 6” diameter line from a 4” diameter will result in lower cfm output performance from the fan. So yes... totally inefficient. You will be wasting electricity this way, plus shortening the useful life cycle of your equipment.