How to cool grow room down

85 isn't the end of the world, you've got the idea pulling cool air in the bottom and exhausting hot air at the top

only thing you can do is get a higher cfm fan, or additional a/c to cool ambient temperature

 

What kind of extraction fan do you have? 85 is not the end of the world, but getting a better fan will help bring that temp down. As long as you have adequate intake holes for ventilation, you don't need an intake fan.

 

An 11 degree difference under a 400w bulb is actually pretty severe. Is it in an air cooled hood? My assumption is that it is a wing reflector. AC Reflectors make a HUGE difference when it comes to cooling efficiency versus open wing systems and this might be the piece of hardware that you need.

The ballast is outside of the tent, right?

With the tent you have and the light you are running a 4" 180cfm fan might be able to offer the exchange rate you need as long as there are no bends in the ducting. I find myself running a 6" 400cfm fan on a speed controller set pretty low with the option of cranking it up if need be.

An intake fan will help. I get much better cooling when using a lower wattage axial fan at the intake. If you have a spare fan around this is worth a shot.

The ideal indoor temps are around 76 degrees. With the intake being a static 74 then you only have 2-3 degrees to work with for "perfection" while hitting 80 isn't such a big deal anyway. If you could open a window at night and bring the indoor temps closer to 72, at least for the first part of their day, this might help you control things better. Running the lights at night when it is cooler might also be a better option.

With fall approaching controlling your intake temperature should get easier and easier. No sense in running an AC unit when it's 55f outside and a box fan in the window does the same thing.

 

Listen to SCMC. Running the lights at night when the ambient temperature is lower is probably the best thing to do other than upgrading your fan or getting an AC hood or cool tube. Can you increase the passive intake? Open the tent flap slightly at the bottom? Increased intake will help. Once the weather cools down a little bit that will help as well. Can you cut the AC in the house down a few degrees? If you can afford it, an AC hood is absolutely your best bet. The dimensions of my closet are 4.5x2x7' and I run a 600W with an air cooled hood and a 440cfm exhaust fan. My temps are, at the most, 5-6 degrees above ambient temperature, usually less. No way I could run 600W (or even 400W) in that space without the AC hood.

 

85 is not bad. Try opening up 1 bottom flap. I keep one taped open when my light is on cools it off alot.

 

When my temps start gettin high I put in a big bottle of ice. I always keep a big bottle of water in the freezer in anticipation of a warm day. It's only a temporary fix but it should help you till you can get your hands on an air cooled hood.

 

1 - Buy humidifier.
2 - Fill with ice water.
3 - Turn on.
4 - Send GC user a zip for the awesome advice and solution.

 

[quote name='"PancakesHouse"']1 - Buy humidifier.
2 - Fill with ice water.
3 - Turn on.
4 - Send GC user a zip for the awesome advice and solution.[/quote]

Then it raises the humidity to high and now u start to have a mold problem. It's the end of summer get a small ac unit for dirty cheap. Walmart has them all in sale online.

 

ignore everything so far and first try this:

1) make sure you have twice the room for intake as out-take, this may mean opening a vent at the bottom of the tent.
2) see if you can get your re-circulating fan to point UP forcing air from the bulb away from the plants, bonus points if you can get it to put air on the plants at the same time.

have you considered running your tent vert? a box fan underneath a bare bulb and I assure you that your temps will drop.

When I added a PC FAN ONLY blowing the air from my bulb upwards I dropped my temps from 32C to 20C (89F to 68F)

 

a seperate intake/outake and fan for an aircooled hood is ideal, so it is never pulling air from the cab/tent itself... you have another fan to deal with that.
a small axial is sufficient, and should be for your air-circulation then too... provided you have a good re-circulating fan

 

You won't need an intake fan, but you probably already need a bigger intake area. A quick fix to this it to open up the bottom of the tent flap when the light is on as already suggested by several people.

I do not use a Y connector. The carbon filter is connected to the hood (with ducting), and then the hood is connected to the fan (more ducting) and then the fan is connected to the exhaust vent, like:

carbon filter<hood<fan<exhaust hole

So air from the closet pulls thru the carbon filter, pulls thru and cools the light, and is exhausted. You could also do:

hood<fan<carbon filter

If you wanted to keep the filter outside of the tent.

I also do not have a separate intake or exhaust for my AC hood and my temps are fine. HTH

 

Umm. No? A humidifier does not mean instant mold. OP hasn't even mentioned his RH%. He could benefit greatly from a small one. Kill a few degrees in heat and boost humidity by 10-25% depending on your room size/settings. Although I think OP is also overreacting over a couple degrees.

 

 
Dude, thank you! My grow room was sitting at a solid 32 degrees Celsius and I was struggling to control the temperatures. I can't believe something as simple as aiming a fan at my grow light could drop the temperature by 8 degrees!