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This is part of thread I posted elsewhere, given some of the questions and pms I've recently received asking about the circulation systems used in my rack setup I've decided to post it here. This thread will outline the construction of an In-Tank Closed-Circuit Systems and two different methods for powering it.

First, I suggest that you do a search for some of the other threads here on Dendroboard regarding "Air Circulation". There are many methods to achieve this goal - what I present here is one designed to fit my particular needs.

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)

Most of the materials. Some additional items used for an External System are also in the photo (i.e. the PVC fuse box and "L" connector):


3/8” Brass Nipple:


IN-TANK SYSTEM

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 now be swiveled and turned to point anywhere in the vivarium.



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:



New Fan Speed Control and Temperature unit in place:

 

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Awesome post! What a slick and professional looking set up. I'm a little curious, are in tank circulation systems designed to keep up humidity but give water sensitive plants a dry out period?
 

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Discussion Starter · #3 ·
Awesome post! What a slick and professional looking set up. I'm a little curious, are in tank circulation systems designed to keep up humidity but give water sensitive plants a dry out period?
Thanks - still working on bettering this, but I am glad you like where it is at.

Air circulation helps keep fungus and diseases in check and benefits the overall quality of life of the vivarium. Both the plants and animals will benefit from reducing the amount of stagnant air.

This system is not designed to introduce the arid air from outside, or force the humid air out of the vivarium. It simply moves the warm humid air -already in the vivarium- around so that there are not temperature drops or rapid drying. Other closed circuit systems accomplish this as well, but the advantage of an in-tank system is that you get much more efficient use of the fan (rather than having it suck up air and push out air through pvc pipes). Using the same type of fan I get twice as much air movement with the In-tank system running at 50% than my external systems running at 100%.
 

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I really like the in tank setup. I've heard some orchids require quite a bit of air movement.
 

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how well can these withstand misting?

This is amazing, I think I will add these to all my vivs.
 

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I've had a cheap computer fan running for about 3 years nonstop with no problems. I've had to change the power supply though.
 

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Leo, this is superb. I am curious as to what effect, if any, it has on glass condensation? That's my primary motivation to have an internal fan.
 

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Would larger tanks need multiples of these? say the 36X24X18 exo.. would two suffice?
 

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Discussion Starter · #10 ·
Leo, this is superb. I am curious as to what effect, if any, it has on glass condensation? That's my primary motivation to have an internal fan.
Thanks John. I am not quite sure of the effect on glass condensation since all my tanks have circulation so I don't have anything to compare it to. The glass on my tanks do fog over, but not to the extreme that I have seen in the no circulation/no ventilation set-ups. I suspect that pointing the fans towards the front glass would indeed help clear it up a bit. I should mention that none of my fans are positioned this way, they all point towards orchids or towards the rear of the tank.

I rely mainly on adjustable top/front ventilation for controlling the condensation on the front glass - but have it closed 90% of the time since most of my frogs are more active when the glass is slightly fogged.

Would larger tanks need multiples of these? say the 36X24X18 exo.. would two suffice?
I would think so. It all boils down to how much air you want to move and what your goals are. For example, if you have several orchids (that do well with air circulation) setting up one fan per orchid would yield great results.

For a tank that size, I would also consider and external system with a more powerful fan.

In the end I don't think that there is a perfect amount of fans or perfect amount of air movement that can be achieved. The goal should be to get some enough circulation in order to keep the air from becoming stagnant.
My high tech solution for measuring air stagnation, is to use my sense of smell. Those vivariums with good amounts of circulation smell very crisp like a forest after a rain versus the boggy smell of vivariums with static air.
 

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I believe the 90 degree elbow and fuse box were extra materials to be used in an outside of tank air circulation system.
 

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Discussion Starter · #13 ·
What was the 90 degree elbow used for?
I believe the 90 degree elbow and fuse box were extra materials to be used in an outside of tank air circulation system.
Yes, they were for an external set-up:



I copied this design from an older DB thread which I am having trouble finding. But here is a very good thread detailing a slightly different version:

http://www.dendroboard.com/forum/parts-construction/44176-enclosed-air-circulation-system-you-can-make.html
 

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how well can these withstand misting?
If you became concerned with that, you could put both fans and misters on timers (many people already do that for their misters) with the fan(s) turning off for a brief period of time surrounding the misting, but my experience has been that these fans are pretty resilient to humidity. I imagine that others experiences have been similar.

also, newegg.com was mentioned for fan controllers and the like. They also sell fans. Certain fans produce more noise than others and more airflow (CFM) than others. Generally speaking, higher CFM means higher RPM which usually equates to more noise, but that isn't always the case. For those who enjoy the quiet serenity of a viv tank, or the trickling sound of a water feature, a noisy fan wouldn't be a good idea. If it's a concern for you, you will want to do your research into a quiet fan because some of these can be loud. I have some 90CFM PC case fans that sound like hairdryers! That's extreme, but just look at the dB compared to the CFM. The 40mm case fan mentioned for this project is pushing 8.5cfm. I'm looking right now at 40mm fans that do 6cfm at the noise level of 12dB. Those are being billed as quiet types, so just do your research as you shop.
 

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Does anyone know where I can buy the black 2" - 2.5" pvc reducers as well as the funny pipe end pieces? I can't find those anywhere.
 

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does the funny pipe end cap have a different name? I cant even find it on the toro website.
 

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does the funny pipe end cap have a different name? I cant even find it on the toro website.
My dad and I needed some to work on our sprinkler system this spring and we couldn't find it either. We think it may be discontinued or in short supply but we did see some last weekend hidden under the shelf in home depot.
 

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I just called toro and they didn't have any clue what I was talking about.. will other caps screw onto the swing joint? Also, does the black pvc reducer have another name? I cannot find black reducers anywhere, nor can I find the appropriate size reducer.
 

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Does anyone know where I can buy the black 2" - 2.5" pvc reducers as well as the funny pipe end pieces? I can't find those anywhere.
Menards carries the 2"-2.5" black pvc reducer.

They also carry them here:
Find ABS Fittings and other Pipe Fittings ABS at Aubuchon Hardware

does the funny pipe end cap have a different name? I cant even find it on the toro website.
Look up Female hose barb fittings.


US plastics carry them
Search Results | U.S. Plastic Corp.
 

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thanks a ton! Where on that site is the 2.5" - 2"? I saw the 3-2 and the 2 - 1.5.

Would the female hose barb part work once the barb is removed? I think the cap worked well because it was closed on one end which allowed the brass nipple to be screwed in securely.
 
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