DIY Air Circulation
This article will outline the construction of an In-Tank Closed-Circuit Systems and two different methods for powering it. I developed this to use with vertical conversion kits in 10 and 20 gallon tanks. Given that there is not as much length in these tanks as you find in the larger exo-terras and zoo meds an External System would result in the intake and exhaust openings being very close together. Furthermore, this In-Tank System reduces the size and number of holes to be drilled into the glass. All you need to drill is one ½” hole (same size opening as that used for attaching MistKing nozzles).
What an In-Tank System looks like:
With the exception of the fans, you can pick up ALL the materials at your local Lowes or Home Depot.
The fans can be purchased online at a computer part store (such as newegg.com) or at a local electronic or computer store (I bought mine at Fry’s Electronics).
In-tank System:
1. 40mm PC Box Fan (8.5cfm, 12 volt)
2. 2” to 2.5” PVC pipe Reducer Fitting
3. Fine mesh screen
4. ½” Funny Pipe Barbed nozzle
5. ½” Funny Pipe end cap
6. ½” Elbow Swing-Joint (I use Orbit brand Elbow Swing-Joint 90º)
7. 3/8” Brass Nipple (1/8" opening)
8. 3/8” Hex Nut (make sure it fits around the Brass Nipple)
9. 4x Plastic Risers
Other Building Materials
1. Drill
2. 3/8” circle bit
3. ¼” drill bit
4. GE II 100% Silicone
5. Toothpicks or tongue depressors (for spreading silicone)
6. PVC pipe cutter
7. Soldering Iron and Wire
8. Razor Blades
9. Some extra Fan Power Extensions (depends on the type of set-up you are using as to whether or not you will need these)
The first stage is to build the fan container. This needs to allow airflow while impeding a frog (or other animal) to make direct contact with the fan. The container for the fan is the PVC 2” – 2.5” Reducer with some minor modifications to allow it to connect to the rest of the assemblage.
We want to add a method for the reducer to screw into the Elbow Swing Joint. This is accomplished by taking the ½” Funny Pipe Barbed nozzle and using PVC cutters to cut off the nozzle.
This leaves us with a small male threaded pipe. This is siliconed to the 2.5” end of the Reducer and a ¼” hole is drilled to allow the wires from the fan to pass through as such:
Next, we want to add some fine mesh screen to the inside of the PVC Reducer. Simply done by layering some silicone and pressing down an appropriate sized cut piece of the screening.
Take the fan and cut off the 3-pin Molex connection, then place it inside the PVC Reducer so that the front of it (where the air blows out) is towards the smaller opening of the Reducer. Thread the wires out the previously drilled hole and secure the fan with dabs of silicone on the four corners. In the photo, the front of the fan is facing down.
Note: The probe that you see in the photo is a temperature sensor. I include these to plug into my Fan/Temp Controller but they do not constitute part of the Air Circulation System proper.
Now dab some silicone around the larger rim of the PVC Reducer fitting and place a piece of screen on top. Use toothpicks or a tongue depressor to firmly adhere the screen to the silicone.
Let it dry then use scissors to cut out the excess screen. At this point, I like to add another layer of silicone over the top and spread it so that it adheres to the outside edges of the PVC fitting forming a “ring” around the screen.
At this point the fan is now completely encased in the PVC Reducer.
Now, take the ½” Funny Pipe end piece and unscrew the cap. Drill a 3/8” hole into the center of the cap and screw in the 3/8” brass nipple.
Almost done. Thread the fan wires through the ½” Elbow Swing-Joint and through the brass nipple in the end cap.
At this stage I solder the Fan Extension wires to the fan wires thereby adding a 3-Pin Molex connection to plug into the power source. I also add Molex connections to the temperature probe so that it can plug into the Fan Controller.
Screw all the pieces into each other to complete the assemblage:
To install it into your vivarium you will need to drill a ½” hole into the vivarium top.
Position the fan assemblage inside the vivarium. Add enough washers to cover up the area of the nipple that is not threaded. Screw the 3/8” Hex nut to the top and pat yourself on the back as you have installed an In-Tank Air Circulation system.
This fan system can
POWERING FANS INTRODUCTION
At this point you are ready to power up your fans…but are faced with the issue of how to wire a 3-pin or 4-pin Molex connection (generally runs on DC current) to an AC wall socket.
This is the most daunting step for first-timers given the amount of questions I’ve seen. However, it shouldn’t be. This is quite easy and you do NOT need to be an electrician or even very knowledgeable about electrician “stuff”. You DO however need to be smart about it and put your safety first. DON’T work on open wires with a live current going through them, make sure that everything is unplugged before soldering or twisting the wires.
First, get to know the Black, Red, and Yellow Wires.
Black= 12 volt Current
Red= 5 volt Current
Yellow= RPM (Revolution Per Minute) sensor. This wire is for the most part useless unless you are actually connecting the fan to a computer that will monitor the RPM of the fan. For most scenarios you will simply cut it out or tape it out of the way. However, if you are using an advanced Fan Controller to monitor the fans, you will want to keep the yellow wire connected as it will send data regarding the fan speed back to the controller.
The goal is to get the AC current from the wall into the black and red wires of the fan. To do this you will need an AC/DC converter. Most converters I’ve seen these days are variable voltage (giving you the option to decide how many volts to output). These generally range from 5v to 12v, running at lower voltage will make the fan spin slower, higher faster.
Here is one I’ve used . By moving the slider I can adjust the voltage exported and hence the speed of the fan:
SIMPLE 1 FAN CONNECTION
Cut the end connector off the AC/DC converter so that you expose the two wires within the cable. The plan is to connect those two wires to the black and red wires from the fan.
If you switch black and red (or inversely wire them) the fan will spin in the opposite direction. So test this a few times by lightly twisting the wires together and carefully plugging the converter in to make sure the fan spins in the direction you want.
Once you get the fan spinning in the correct direction you’ll want to make a more permanent link between the wires. First, UNPLUG the power source! Soldering is fast and easy, but twisting them tightly together could work if your squeamish around a soldering iron or accident prone. After, you’ve connected them, insulate the open wires with electrical tape and you are done!
MULTIPLE FAN CONNECTION
*** WARNING – Extreme Electrical Sexiness ***
Here is where things get fun and you can really let that inner Geek loose. You can purchase a multiple Fan Speed Controller from a computer or electronic store (again, newegg.com is great place, as is Fry’s Electronics) .
This is the one I used before starting this thread (runs about $20) and can power up to 4 fans and allows you to adjust their speeds using the knobs.
This is the one I recently gifted to myself for my Birthday…Simply put, this thing is just badass! LCD screen, runs 5 channels for fans, and includes 5 temperature probes. Bells and Whistles galore!
The advantage of using a multiple fan speed controller (aside from the obvious ones of more fans, speed control, cool factor, etc.) is that you only have to worry about wiring one power source. The fans will all plug into the controller using their native Molex connections. It makes the systems much more modular – simply plug and play.
For a Fan Speed Controller (like my previous one) that uses a 3-pin Molex connection for the power source, you simply cut the output end of the power cable and wire it directly to the AC/DC adapter.
My new system uses a 4-pin Molex power cord and rather than dealing with the extra ground currents, I found a 4-pin Molex to Wall adapter at newegg.com ($12).
Once your power source is connected to the Fan Speed Controller, connect your fans using their native Molex connectors and viola!
Fans and temp probes connected to Molex extensions from Fan Controller:
