Vivarium air flow

[orchid_guy]

I am new to this forum, so please forgive me if I am addressing my question to the wrong group or if my topic has appeared in another similar thread.

I am building a vivarium to house some of my orchids, but am not clear about air flow/ventilation.

I am planning to install 2 fans at the top of the vivarium, under the lights. (50 gallon aquarium).

One fan will blow air down, and the other suck air up and out. Is this setup appropriate?

Is ventilation the same as air flow?

And do I leave the fans running all the time, or set to a timer?

I have looked on the web, but have seen nothing that specifically talks about this.
Any help would be greatly appreciated.

[Epiphile]

I don't consider ventilation the same as circulation. Most of my vivaria have fans moving the air, but most are completely closed and do not admit any outside (read dry) air. I can keep humidity close to 100% and still not have issues with rot. Bringing in outside air will affect your humidity levels within the tank, so it's something to consider- it may not be as bad if you have regular watering in your system.

If you point your fans toward the front of the tank you'll get the added benefit of their keeping your front glass clear of condensation, as well.

[orchid_guy]

Thank you, Epiphile, for your response.

You had said that you do not vent your vivarium, just circulate the air. The air doesn't become stagnant, and you have no issues with rot? That does sound encouraging.
Do you leave the fans running all the time?

[Epiphile]

I leave the fans running constantly, yes. I'll open the tank once in a while to drain excess water, etc. but past that it doesn't get much in the way of ventilation.

[orchid_guy]

Cool, thanks

[Tindomul]

I would suggest that if you keep outside air from entering then you need to keep the fans running all the time to keep the air from becoming stagnant. If you decide to let outside air in, and inside air out, then I would place it on a timer. Here is the tricky part, you will have to learn from trial and error when and how long to keep the fans running. I like to keep mine running at night because I had heard that fungus loves wet dark conditions. So I mist my tanks heavily in the morning or mid day and I let them dry out over the day, and then the fans turn on at night.

The benefit of having a closed air system is that you dont water often. This is because the water has no where to go. However, you run the risk of rot is the air movement is not enough and if the medium your orchids are in stays too wet. This would be a great setup for mounted orchids, but not orchids that are potted.

Having an open system allows you to keep both mounted and potted plants, but you have to keep tabs on the humidity levels.
Hope this helps.

[orchid_guy]

Actually this is a good idea, I think, to keep the fans on at night. I was planning to have both mounted and potted plants in the vivarium, so I will probably have some ventilation. I planning to use 2 fans - but now am undecided as to whether I will have them both blow into the aquarium, or one in and one out. Think it will be trial and error. I'm guessing the vivarium will retain high humidity just by spraying, or from the other plants? I have heard that misters are also used - was thinking also about that. Anyway, thanks for your help - looks like lots of trial and error. Will keep you posted.