Having trouble keeping humidity up when lights are on

[CrimNI]

Hi Everyone,

I have been having trouble keeping my humidity up when my t5 HO lights are on. I have a 4' six bulb fixture. The bulbs are arranged with three grow and three bloom. The bottom of the shelf is about three feet from the lights. The RH only gets to about 35% with the lights on and 50% with them off. I have one cool mist humidifier that is on almost all day. It is located to the bottom left of the enclosure. There is space for the humidifier to access the enclosure if it is completely closed off right above it. I'm using seedling trays as humidity trays that I got from Walmart, they are filled with water. The temperature can go up to 92 degrees if the enclosure's front is rolled down and about 82 if the front is rolled up. I have tried spraying down the entire thing to see how well that would work and the RH only goes up about 5% or so. I have a fan in the enclosure if needed but I'm not using it because it only brings the RH down, and the humidifier allows a little air flow. I haven't put any of my plants in it because I really wanted it to be perfect before putting them in this environment. I'm concerned that there is a problem with how I've set up my enclosure and if there is anything I should change. Should I invest in a better humidifier or get another one?
Attached are pictures of my setup and a fan that's located in the top left corner of the enclosure.

[CrimNI]

Sorry, forgot to post the attachments.

[The Orchid Boy]

Hmmm... I have no problems humidifying my 11'x12' bedroom to 65%-75% with 1 cool mist humidifier. I have 1, 4 tube HO T5 fixture and 2, 2 tube T8 fixtures. Maybe your humidifier isn't as good? I got mine from Walmart, it is a Vicks brand, filterless, cool mist humidifier, like the one here: Vicks Filter Free Humidifier - Walmart.com

[31drew31]

Is the entire enclosure sealed or is the top open? Are you sure your humidity gauge is correct? Normally after misting humidity should rise quite high (80%+) while the water evaporates, even with an open top.

Also, once it is filled up with plants humidity will rise some because of the evaporation of the water in the pots.

Not sure what plants you are planning to grow inside, but whenever Ive grown plants in an enclosed space Ive kept the lights outside of the terrarium or enclosure with a glass top. I like to leave about a 1-2" gap along the top on one side for air exchange. If you're having trouble with heat, put the fan on the lights and keep the lights 2" or more above the top.

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[Bud]

What is your grow zone?
I think you have it all down pat....and working well for you....all the necessary ecquipments check out....
unless you have a really dry zone arid atmosphere that sucks out humidity bigtime....even indoors

[isurus79]

I think if you put some kind of a well on the bottom of the enclosure and fill it with water, that will help. It seems like your enclosure is not sealed off at all on the bottom, which is your problem. Having misters that go off several times per day will help and having some kind of water catching recepticle (like a well) should boost humidity too.

[billc]

Steve is right, you need to close off the bottom or maybe extend the sheeting all the way to the floor. I have the same style shelving unit wrapped in plastic sheeting that goes all the way onto the floor and my humidity level gets up to 80%. I have a cool mist humidifier on a timer 15 min on, 30 min. off, and the RH goes as low as 55 and as high as 80.
Your set up looks nice. What are you going to grow in it?

Bill

[CrimNI]

Thank you all for the replies! I tried buying a new humidifier to see if that was the problem. I got a Crane drop shape ultrasonic cool mist humidifier. It's neat but the humidity hasn't really changed. Should I put the humidifier in the enclosure? I know a few people commented that the bottom needs to be enclosed, but I do have about 3/4s of it covered if you look really closely and the end not closed off for the humidifier. Should this not be like this? The top is not enclosed, I thought the lights would be cover enough to keep humidity in, but maybe some plexiglass would be good. My grow zone is my bedroom, it's an apartment so it's a small bedroom but the door does stay open. I do try and mist to see what that will do but I thought the “humidity trays” would catch the water and evaporate, but all that seems to happen is that the water gets warm from the lights. BillC, I can try enclosing the entire stand in plastic so the humidifier doesn't go into the room. That is a good idea. Should I not be using the mylar to reflect the light? Is that making it too hot and losing the humidity? I could just use all plastic. I plan on growing mainly catts but I have a few phals, and an angraecum. Thank you for the complement Bill. I am really excited to put my plants in here to start really growing but the humidity being so low is disheartening.

[isurus79]

Its definitely a lot easier to get the right environment in a small enclosure than in an entire room! Closing off the terrarium should be your first focus IMO.

[billc]

The humidifier should be in the enclosure. You'll probably need to put a timer on it because if it runs all the time you'll have dripping water on all the surfaces.

Bill