[kychris]

Ventilation is one area of my build that I've been pondering over the last month. I see a lot of people use small 40mm fans mounted in the tank or outside via ducting.

From my RC airplane days I know that the smaller the fan, the less efficient it is. I started trying to incorporate a big fan by using the same ducting that is used for the 40mm fans. But also, the smaller the ducting the more the resistance.

Then it struck me that throughout our house we have large ceiling fans to circulate air.

Has anyone tried using a large computer fan in the 200mm range on the ceiling of a viv? I figure using standoffs on each corner mounted to the top glass to allow it to pull air from behind. In front you would only need a large mesh to keep the frogs out. Something with mesh the size of a strawberry basket.

I'm thinking about ordering a big computer fan but thought I'd see if this has been tried before.

Thanks!

 

[kychris]

That is a very interesting idea, though it may be difficult finding the correct balance between how low you can mount the fan and how obtrusive it will be in your viv. There has to be an optimum distance for optimum air flow.

One more thing to be concerned about is noise. I have a i think 180mm on the side of my desktop and it is fairly loud. I'm not sure I'd personally be okay with that in a viv. You could of course reduce its voltage.

Good luck! I hope to see how this goes, it seems like an excellent idea.

I was thinking of just mounting it a couple centimeters from the lid. Just enough to allow air flow.

Noise is the main reason I want to use a larger fan. You can run it at a lower speed and thus quieter but still get the same output as a 40mm fan.

 

[kychris]

I would also be concerned about the airflow being too high. I'm not too sure if it will be a problem, but I would consider:

1) the sheer airflow will be strong for such tiny creatures, especially in close proximity of the fan (I would imagine FF's getting blown around). most tanks are not very tall, combined with height lost from false bottoms and then adding in considerations for landscaping/hardscaping that can be climbed...the distance from the fan to nearby tank elements won't be that big.

2) you will dry out the area directly under the fan (which will cause a chain reaction of problems)


I think noise issue can be (mostly) avoided by buying fairly good silent fans.


You are solving the "large volume of air moved" problem, you are doing so at "high velocity". In order to cycle the air in the tank withOUT disturbing the tank, it is important to do so as gently as possible (ie low velocity->low pressure changes); I think this is why most people use multiple smaller fans; the airflow is less per fan, but it is also distributed over much more of the tank area, causing a less volatile disturbance (or none at all)



I don't know if others run their fans pointed INTO their viv, but I have never had good results with this method. My humidity always plummets, and in particular the area that gets the fan pointed at it always dries out. I should note though that I do NOT use glass tops on my tanks (they are all screen). My fans always point "across" the tops of my tanks/lights


EDIT: just to clarify on a few things...if you are planning to use only 1 200mm fan to replace several 40mm fans you will need to run that 200mm fan at a relatively high speed.

On the other hand, if you were to use MULTIPLE 200mm fans, you could slow them way down and still get the same airflow...but I don't necessarily see a benefit here (it seems more like an equal alternative)


What exactly do you mean by "efficiency"? Are you talking about the "power use to airflow" ratio or something else? The power savings will be negligible I'm pretty sure (and you still run into the problems above if you only have 1 200mm fan to achieve the same airflow as several 40mm)

1. The airflow can be adjusted.

2. Not if the fan speed is slow. I also thought of trying the fan reversed with it blowing to the lid and then down.

Humidity dropping would only be a problem if the fan is drawing in outside air. I should have specified that I'm talking about a solid glass lid with a fan mounted to its underside.

Here's the data: A Delta 40mm produces 22CFM at 57dB. The loudest 200mm I found on newegg during a quick scan produces 166CFM at 37dB. So actually, you could run one 200mm fan at much slower speed to produce the same airflow as 4 or 5 40mm fans with much less noise.

By efficiency I meant airflow related to noise. Power draw is probable negligible.

 

[kychris]

Sounds like a good idea to me. How would that effect the light though? Or do you think it would not obstruct that much light? I guess that would be alot different on a 10 vert than a larger tank w a bigger lid.

This is the big problem on smaller tanks. I have a 44 pentagon and a 18x18x18 so there should be room around the fan for lighting. I'm using the LED lights from lightyourreptiles.com which should give me more room since the LEDs direct all of their light straight down. Another benefit of going LED.

Also they do make clear fans in the larger sizes which at least will minimize the light loss if a light has to be placed over the fan.