Recently, I got around to building a ventilation system for my 55 gallon terrarium. My goal was to include air from outside the terrarium. The humidifier was to remain a vital role as well. The key is to balance the effectes of fresh air and humidity. Here's the pictures for all you visual learners, while my rambling post follows.
Here's what I did: glued a 12v CPU fan to a PVC "U" joint I had laying around. Connect the 12v wiring to a 9v adapter. I wasn't about to spend $20 for the cheapest AC-DC adapter out there, so I scrounged up a 120v - 9v 1000mA adapter I had in storage. Although the 12v-9v issue concerned me at first, I set the fan on a timer so it runs at 30-60 min intervals a few times a day. This way, its not running all the time and shouldn't run too hot from low voltage. So far, so good. [img]http://www.**********.com/iB_html/non-cgi/emoticons/new/smile.gif[/img]
The humidifier setup has already been explain HERE, so I won't go into detail about it on this post.
The fan itself is outside of the terrarium, so moisture shouldn't have a negative impact on the electrical components.
Results From the pictures, you can see the locations of the 1st and 2nd temperature / relative humidity (RH) gauges. Temperature decreased at the 1st gauge by 1 degree F over the course of the trial (33 minutes). 2nd gauge gained .5 degrees. RH at the first gauge decreased from 91 to 84 RH, while the 2nd gauge went from 86 to 80 RH. I checked the readings every 3-5 minutes, and ended it when I got 3 consecutive identical readings from both gauges.
Conclusions Sensitive SE USA Pinguicula are located near the air input side of the terrarium, and the water level decreases here more substantualy than other trays placed throughout the terrarium. The pings are doing well; from my personal observations, I've noticed P. planifolia will decline rapidly in times of low humidity.
When the humidifier is on at the same time as the ventilation system, one can see the mist swirl about the tank and exit to the right side.
Now that Autumn is upon us, our natural gas forced air heating turns on to keep our house at approx. 70 degrees. The drier air has had an effect on the RH in the tank. Gauge #1 commonly goes down to 68% RH.