With the feeder colonies taking off, I have discovered the need to cull larger amounts of mice in a quicker way then current ways. I read about building different co2 chambers on different sites and basically came up with my own design. Thought I would pass it along, it costs a little with initial set up, but if you have some of the key parts around the house, then it is pretty cheap. You can easily modify it with a different size pipe if you want larger prey items or multiples (such as rats); I'll list what I did, but keep in mind, there really isn't a limit on what you can do.
Parts list:
1 -- 2' section of 4" PVC pipe
2 -- 4" to 3" PVC adapters
2 -- 3" PVC threaded clean out ends
2 -- 3" PVC clean out caps
2 -- 1/2" threaded female ball valves
2 -- 1/2" adapters with a threaded male end and threaded female end
1 -- CO2 tank (paintball gun tank)
1 -- CO2 high pressure hose and 1/2 connector
Chamber parts:
4" PVC pipe, 4" to 3" adapters, 3" clean out ends
The clean out ends should be threaded to fit the caps: In some stores they sell the ends with the caps for a cheaper price so look around.
adapter, ball valve, end cap
CO2 Hose
CO2 Tank
You will also need PVC cement & Primer: these can be bought in a set for a cheaper price. If you never have used it, first you take the purple primer and put it on the ends (both) that are going to connect together. Then use the cement around one of the ends and push together. Less is more with this stuff and if you get the primer on anything expect it to be purple for the next 30 years. Make sure you use proper ventilation.
Join the clean out end with the 4" to 3" adapter: do same for other end as well. Becareful not to get anything on the threads of the cleanout ends.
Then join ends you have just made to each end of the 4" pipe. I didn't take a pic of this, but you can figure it out from later pics if you are having trouble.
Put aside and let dry. Now time to assemble the valves. Cut or melt hole in the middle of the end cap square. I personally used a drill press to do this and then since I had it, I threaded the hole with a tap and die set, but really that is not needed. Even if your hole isn't perfect, don't worry about it, you can cement around it if need be to cover any cracks, but it doesn't need to be air tight as we will discuss a little later.
After you get the hole, stick threaded end of adapter through the hole to the outside and screw on the valve.
Now do it again.
After drying time on the main chamber, screw the valve assembly you just made into both ends of the chamber. Both ends should then look something like this.
My hose came complete with a 1/2" threaded adapter so I screwed that into the one end of the chamber and attached the hose to the tank and the chamber end.
And you are ready to go!
HOW TO USE:
This is meant to humanely put down mice, rats, etc (whatever could fit in tube and breaths air.) IT IS NOT MEANT TO PRESSURIZE THE MICE TO DEATH. if you are seeing mice coming out with bleeding out the ears, nose, mouth, etc, then you are doing it wrong.
Have valve at the hose end fully open. Open the valve at the other end just slightly, abotu halfway. Unscrew that end and place prey in chamber. Screw valve assembly back on and assure the valve is open to where it should be.
Open main valve on CO2 tank, slightly, not full force. CO2 that seeps in gradually will put them to sleep and then they die, a quick release will cause the gasping for air and suffering. It does take playing around with this a few times to get it right. Watch the end without the hose and once you detect CO2 coming out, shut the valve at that end and turn off CO2 flow from the tank.
WARNING: MAKE SURE ONCE YOU SHUT OFF THE END VALVE YOU IMMEDIATELY TURN OFF FLOW OF CO2. If not you run the very real risk of blowing up the chamber due to pressure. That is why I said you may not want to cement the valves in if you don't need to. The chamber doesn't need to be absolutely air tight, CO2 is heavier than O2 so any small leaks should displace O2 before the CO2. The hose does have a pressure disconnect on it but it is rated at 300PSI where the pipe is only rated at 200PSI. So I think pipe will go before hose disconnects, but I really don't want to test that theory out.
If you want to disconnect the tank to use on a second chamber, you can shut off the other ball valve on the end with the hose (AFTER FLOW IS SHUT OFF).
Wait a minute or two and open valve to allow pressure to be released. Screw off end, and dump out your prey items ready for feeding or freezing.
COST:
All the PVC (pipe, ends, valves, adapters, etc) cost approximately $30.00 at Lowe's.
20oz CO2 tank from walmart costs $30 bucks, another $7 if you want one filled.
CO2 Pressure hose was most expensive and hard to find. Found it at Dick's Sporting Goods and it was $50. The adapter that fits the 1/2" threaded valve end came with it.
It will pay for itself in time and it does allow you to a large amount of mice at once. Upsize to the 6" and you can do very large rats with no problem at all. But if you do, you'll probably need to change the sizes of the 4 to 3 adapters to 6 to 4.
If you have the paintball tank and hose, it is relatively cheap to make.
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