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Discussion Starter #1
Sorry to post another question, but I'm wondering if vents will be needed for a vivarium that will have internal air circulation (computer fans). Any help would be greatly appreciated. Thanks!
 

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Discussion Starter #3
Thanks for the info, Doug. I know that neither is absolutely necessary, so I guess I should rephrase my question: If you use a form of internal air circulation for your vivarium(s), do you also have vents for your vivarium(s)?
 

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I have mixed feelings on vents. My first tank was a 30 gallon tall and it was air tight. I did create a dual loop circulation system which I could reverse the flow. It had one input in the middle with an output on each side (or reverse with two inputs and one output) to create two circulation loops within the tank. This worked well for my setup. I felt that opening the tank on a daily basis to mist and feed provided more than adequate air exchange.

On the other hand, I had two 10 gallon verts that both had vents at the top. I would loose moisture through the vents and found many of my plants didn't fare well up there. The combination of dry air and heat from the lamps did not work. I ended up using some clear plastic to cover the vents about 80% and that helped. They were too small to deal with a circulation system.

I'm planning out a large tank, roughly 100 gallons, plywood construction with sliding front doors. I will definitely be installing a circulation system in it, but I've yet to decide if I will put in outside vents.
 

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i doubt you'll need ventilation (even passive) in combination with the circulation. i personally prefer the sealed circulation myself, since it keeps humidity pretty stable (as compared to a vented tank) while still allowing the plants to dry sufficiently.

james
 

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i KNEW i would get to use this!! (Ed always post stuff i know will be useful)



"One of the problems with people sealing thier tanks tightly and maximizing the humidity of the tank 24/7 we are actually preventing the frogs from cooling themselves through evaporative cooling. See the following abstract here JSTOR: An Error Occurred Setting Your User Cookie (the link is valid even though it says there is an error). If the humidity is low enough the frogs can actively uptake water from the substrate and allow it to evaporate cooling the frogs. Many in the hobby remove that option by how tight they seal the tanks which takes that option away from the frogs."

I have always been a pro vent for many reasons but here is the back up on how frogs can use it.
 

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I like to use both vents and circulation, myself. Remember that it is very easy to block off part of a vent with a piece of plastic cut from a plastic folder or report cover.
 

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Wouldnt air circulation assist in evaporative cooling much better then a tank with almost stagnant air that is slightly drier? From that link, its seems a frogs posture and leg spread is what they use most often to regulate their internal temperature. Even though the air is more humid in a sealed tank, water evaporates at a much higher rate from surfaces when without a fan. Isnt that what evaporative cooling is all about?
 

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I only have one 20 long tank, and it is sealed with a computer fan in one of the corners.

Since temperatures have dropped recently, I've installed a under tank heater on the bottom of the tank to boost the temp in my tank a few degrees (I don't use a lot of hot lights). I've noticed that ever since the heater went on, my viv looks a lot "steamier" -- there is a lot of condensation on the glass, and previously there wasn't much condensation at all.

On the side where I have the fan however, there are definitely some spots where it looks drier. There is an area on the glass where it is perpetually dry near the fan, and I'm pretty sure it's because of the air movement.
 

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Wouldnt air circulation assist in evaporative cooling much better then a tank with almost stagnant air that is slightly drier? From that link, its seems a frogs posture and leg spread is what they use most often to regulate their internal temperature. Even though the air is more humid in a sealed tank, water evaporates at a much higher rate from surfaces when without a fan. Isnt that what evaporative cooling is all about?
I've got to say you're confusing me with that Grimm. Evaporative coolers always have a built in fan. To use evaporative cooling in professional greenhouses they use huge fans over entire evaporative walls. As an ex-coral farmer we used to put fans blowing across the tops of our grow out vats and they could drop but quite a few degrees and we had to start putting more water in the sump for the added evaporation.
 

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Cooling by evaporation does not require a fan. What happens is that when the air is dry enough the heat from your body(or frogs heat from being in a hot environment) goes into splitting water molecules. The heat is released in the process. When the air is too wet the water cannot be split and so the heat stays in your body. So evaporative cooling simply talks about the natural process that many animals use. This is why we as humans sweat. Ever been out on a real humid day and it feels a lot hotter than it should for the temperature?? When it comes to greenhouses they simply use the fans to speed up the evaporation since there is no natural heat. As with frogs though, body heat is not required. Their large surface area to internal volume ratio allows for cooling through natural evaporation of the water in their bodies(Im guessing on this i dont know about frogs specifically)

Now as far as this discussion goes I cannot see an internal fan with absolutely no ventilation really helping much. I haven't had my own terrarium yet but internal air circulation with no external air being introduced means the humidity is going to remain relatively stable even with moving air. Just like putting a fan on you on a hot humid day. It doesn't feel as good as on a hot dry day.

Hope this helps.
 

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Now as far as this discussion goes I cannot see an internal fan with absolutely no ventilation really helping much. I haven't had my own terrarium yet but internal air circulation with no external air being introduced means the humidity is going to remain relatively stable even with moving air. Just like putting a fan on you on a hot humid day. It doesn't feel as good as on a hot dry day.

Hope this helps.
I have a 100% sealed tank (ignoring air exchange during feeding), with a hefty amount of internal air flow. I cant say I have noticed any negative effects thus far. Moss is growing like crazy, different orchids bloom monthly, bromeliads have amazing strong root structures, and my once shy frogs are always to be seen. Actually the only remotely negative thing I have observed is a bromeliad leaf drying out from having grown in front of the main air output.

From what I have read here on the forums, in the not to distant past people in NA didnt use either method very often. I have also seen some big time frog collectors/breeders on the forums with plain aquariums with glass laid ontop. No venting, no circulation, just healthy breeding frogs. From those results it is pretty obvious that venting/circulation are not actually needed.

Does anyone have all 3 different types of setups? Have you seen a substantial difference in frog activity/breeding/boldness/plant health/ect..? At least from what I have experienced, the more internal circulation I provide using my variable fan speeds, the more often I see the frogs and the healthier the plants become. I havent used tanks with external air venting yet, so hopefully someone else has tried all 3 techniques. I think the main focus of discussion should be actual observations made through experimentation, and not what we "think" a frog would like most.
 

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I've got to say you're confusing me with that Grimm. Evaporative coolers always have a built in fan. To use evaporative cooling in professional greenhouses they use huge fans over entire evaporative walls. As an ex-coral farmer we used to put fans blowing across the tops of our grow out vats and they could drop but quite a few degrees and we had to start putting more water in the sump for the added evaporation.
Lol sorry bud, maybe I worded it poorly. In the link originally from Ed (quoted by Moty) it talks about frogs increasing their surface area to promote evaporation, therefore cooling their boddies. Kinda like lifting up your arms to air out your pits :p ...So the way I see it, the more airflow, the more efficiently your pits will dry out. hahaha
 

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Discussion Starter #14
I think that I am going to not include any ventilation in my build. From what you guys have said so far it does not seem necessary with internal air circulation. I'll have strong airflow (and the fans will be loud) so I think by having the tank fully sealed it will cut down on noise better than if I have vents. Thoughts?
 

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With regards to evaporative cooling, I think the thing that's confusing things here is the extent of humidity. When evaporative cooling occurs, water evaporates from the wet surface (taking heat with it) and thereby increases the relative humidity of the air in the micro-environment just above the surface. If that air become saturated (100% humidity), the rate of evaporation will be greatly decreased.

In the absence of any air movement, the air above the surface will saturate with water and prevent evaporation. So even though the overall viv may be drier, the lack of air movement means that the micro-environment right above the evaporating surface may in fact be more humid. In contrast, with strong air circulation the air in that micro-environment is quickly refreshed and prevented from saturating. That being said, if all the air in the viv was super humid (say, 99% humidity), I would think that air circulation wouldn't make much of a difference because you'd be replacing saturated air with equally saturated air.

Sorry if I was rambling. I hope that makes sense.

With regards to the original question, in my tank I found that internal circulation alone was great for the plants but wasn't enough to keep the glass free from condensation. I had vents that I generally kept about 80% closed, but I would open them from time to time when I wanted to clear the glass for viewing.
 

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That makes more sense to me now. I was imagining a super humid enclosure with no air coming from the outside lol.
 
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