How to lower temps inside a terrarium?

[swords]

I thought putting a circulation fan in my terrarium would bring the temps down but actually it raised the temps about 5 degrees from 81-86*F(!!!).

Is there a secret to cooling a terrarium lit with Power Compacts w/o hooking the actual chamber up to a window AC and ultrasonic humidifier like I used to for my alpine Nepenthes. I don't need highland temps but I'd like to bring it down from 80 to 75*F max daytime and maybe 65*F at night.

I'd be interested in hearing what you folks do to maintain good temps. I'd like to know your terrarium rooms ambient temp and the temp in the chamber if possible.

[cb977]

I am just in the process of preparing my first "orchidarium" and have been playing with the temps prior to the Masdies arriving. I have an Exo-Terra which comes with a foam backdrop. I shaved away most of the backing and added a few holes. I also shifted it forward in the tank to accomodate 3 frozen water bottles behind it. The temps have dropped by ten degrees.

[swords]

Thanks for your input. However, I'm not too interested in using the frozen water jugs. Firstly cos they take up a lot of valuble space. But also the melting of the ice causes condensation on the bottle(s) which pulls valuble moisture from the air.

In the old days I had a Window AC with a 4" fan and dryer hose connected to the output. Before the dryer hose got to the grow chamber a hose from the output of a 2 gallon ultrasonic humidifier intersected it and humidified the incoming air. Humidity inside was controlled by a humidistat. I was just hoping to not have to go to quite these extreme lengths for "normal" temp tropicals and orchids.

[Ross]

Consider the source of your heat. It is probably the lights. t5 and CF's are designed to operate at 95 degrees F. I intercept most of the heat before it gets into tank by mounting a 3" DC fan on the end of the fixture and blowing through the fixture to exhaust the heat. I also use a sheet of glass (an old pane from a storm door) between the lights and the tank. Here's what it looks like
 

In this one you can see the light fixture as well as part of the aluminum-framed window

 
Their is a fan inside the tank running 24/7, a through wall fan at opposite end running all night pushing humid air out and drying off the plants a bit and the third fan on the lights. Bottom line: the top of the tank under the lights gets about 3-4 degrees higher than bottom of tank so I figure that's the degrees loading. The whole tank runs close to room temp (right now that's 73 degrees F - by tonight it may approach 80-82 degrees if the basement gets any warmer during day.)

[Marty]

My terrarium has 2 CF lights on it and the canopy is closed. Ross is right, you need to get to the heat before it gets into the tank. My canopy is closed and without fans would probably melt the acrylic , but I have three 80mm fans circulating and removing the air from the canopy and venting it out. Fans have speed control so by trial and error I vented enough air to get to the temps I wanted. I then have 2 additional fans in the lid of the tanks (under the canopy) to exchange some of the air inside the terrarium. These are mostly to reduce the condensation so I can see inside of the tank and are turning just at the threshold of condensation. Bottom of my viv is water, which also ads to cooling of the tank. I also have automatic misting inside. When it's all done - I actually have to heat up the water a little at the bottom of the tank to maintain the temps I want.

[swords]

I think I'm going to have to build a hood/canopy so I can set up some fans (and get the CFs up off the plexi-glass). Since this smaller tank was only going to be a holding tank/cutting tank to go with the big eiphyte wall chamber I'm working on I was hoping to not go to much work on it but hopefully a fan in a hood will do the trick.

[andy83]

I don't know what sort of fixture you have on the tank but hopefully it has some good fans built in. You can also place a fan somewhere near the tank to blow across the fixture. The higher it is raised from your tank the better. You don't really want cf's sitting directly on top of most tanks(like you said already).

You said that you have air circulation inside of the tank which is good. Is your tank sealed off? The greenhouse effect starts to take hold with higher lighting methods.

My apartment is at the top of a house so it gets somewhat hot during the summer. 78 or so with the air running all of the time....70 or so during the night. My 40 breeder has a coralife 192watt fixture that sits about 3 inches above the glass. I also have a computer fan that pulls air from a spot on the other side of the tank. I think the main temp reducer for me is the water feature. It gets around 84 during the day and 72 during the night.

Good luck,
-Andy