Since I've been fascinated by Prenolepis imparis, I was wondering if I could find a way to keep temperature steady within their nest. From what I have read, their nests can reach down to 3.6m (http://www.bio.fsu.e...ions/1987-3.pdf and http://www.antwiki.o...epis_imparis). From what I have also read, they prefer cooler temperatures, especially in the 60s F for their nest. During the summer, my room temperature is in the mid to upper 70s F, occasionally peaking into 80s F if we're not home.
I've been toying with some ideas to keep temperatures in the 60s for them within their nesting area. Not everything has gone great in my first couple attempts, so figured I'd document what I've tried so far in case someone else attempts similar.
Cooling thru a reservoir
Idea seemed simple, rather than heating the nest directly, cool the hydration reservoir below the nest. Similar to some of the designs Drew did, there would be either a tile or hydrostone within the nest that would have contact with a sponge underneath for hydration. This reservoir of water where the sponge underneath is sitting is what would be cooled to the preferred temperature. In my mind, it also this seemed like a more natural way of deal with temperature as it's the nesting medium, like the soil, which is holding the temperature.
Initial design thoughts:
- Use peltier cooling to keep costs low (ever price out a chiller for an aquarium, not cheap
) - Closed loop of liquid that would not come into contact directly with the ants
- Closed loop being important as materials purchased from China and other places for pumps and cooling blocks may have unknown containiments that would be hard to remove
- The initial cooling loop would use sterile RODI tubing used for drinking water
Please ignore the cabling and tubing mess in the pics... literally just connecting/disconnecting stuff to experiment with the parts.
One source of cheap water cooling supplies is PC water cooling. Reasonably standard sizes, and easy to get via Ebay, Amazon or Aliexpress. For the first experiment, I used a peltier controller rather than building my own, in theory more reliable. Finding a manual for this in English was a PITA with lots of Googling and some Chinese -> English translation. This unit can do up to 30v at 10amps. However, as you'll see in a later attempt, not great for heavy loads:
Source (https://www.aliexpre...2696684089.html).
For the cooling reservoir, I used a Boxbox drilled out with the RODI tubing for now until I can find a better radiator that doesn't worry me about killing the ants. The temperature sensor for the temperature controller is placed in here as well:
And lastly a couple off the shelf PC cooling parts for the pump and loop reservoir:
Attempt #1
For the first attempt, I tried a single peltier cooler and fan:
Source (https://www.aliexpre...2835505049.html).
Found it ran too hot, and could not keep up with the heat of the pump. Needed to go up another size. The heat sink was hot too the touch to the point of burning when just trying to keep it to about 66F in a room that was 66-70F. Water temperature would routinely be warmer than room temperature.
Attempt #2
I had suspected initially when I purchased the previous one it would be too small, so ordered a double unit as well to try:
Source (https://www.aliexpre...2726378674.html).
Similar to attempt 1, this one was also having issues cooling more than the small amount of heat the pump put out, so again in a 66-70F room, it would get too hot. Heatsink again too hot to touch. Water temperature would routinely be warmer than room temperature.
Attempt #3
Found someone on Aliexpress selling something they called an Aquarium chiller. It contained a significantly larger heat sink, three peltier coolers, and three large fans.
Source (https://www.aliexpre...2825491394.html).
This one actually is showing much more promise. Was able to heat the water to 68F, then drop it down to 65F (took about an hour) in a room that's 66F. The heat sink is actually quite comfortable to touch while heating or cooling. These so far looks the most promising, but not without some challenges:
- The coolers are drawing too much and the temperature controller is getting hot. I'm not sure it was designed for this level of control; may need to find a larger unit, but will probably cost considerably more. In the pic it's sitting on a tile in case it overheats as to not burn the table...
- It's louder than the average PC fans that are running, so may be annoying within the office to listen to.
Other challenges:
- No matter what the eBay or Aliexpress ads tell you, those water connectors are in metric sizes from China, not inches. So mixing tubing sizes is a PITA, or you end up with leaking. Can heat the vinyl tubing and go down a size, but then restricts flow. May be better off spending a bit more to get a cooling block with a tubing size that matches everything else depending on where you live.
- These solutions are using a 12v 15a power supply and a water pump to drive it, not the most cost effective energy wise. The reservoir isn't currently insulated, so wasting a lot of energy there as well to the room.
- Complex setup, prone to several areas of failure (leaks, power supplies failing, etc)
Cooling thru peltier "fridge"
This is my next idea I'd like to experiment with. Currently I have my ants hibernating for the winter in an inexpensive wine chiller I got off Amazon (Amazon Warehouse deal returns has some amazing deals, I got it for 1/4 the cost and not a scratch on it.) The wine or drink chillers they sometimes call "fridges" are also peltier cooler based. However they cool the air within the box obviously vs water like I did above. The nest would instead be placed inside the cooler to keep it's temperature steady. The nest would be air cooled and actively cooled.
- Problem is a lot of the "chillers" have strange settings for their temperature ranges as they are designed really for cooling wine, or sodas, etc. So the temperature controller would require potentially some changing over to handle the 60s that I'd want.
- One benefit (which ironically is usually a negative) for them is that they don't cool that great. Usually the biggest complaint people have with them is they don't get their drinks cold enough as they don't usually get to terribly colder than room temperature. However this temperature range is ideally what I am looking for.
- They are completely enclosed, so would require some modification to allow tubing from the nest to an outworld.
- Internal space on the small ones isn't a lot, so may not be cost effective for a reasonably size colony
- Can't really observe the colony directly, need to look thru glass (if it has it), or open it the door.
- Humidity concerns? I wonder if the humidity will drop within the box as it's cooler, but I don't know without trying it.
- Should use less power than the other solutions I tried, as only runs when it needs to, and closed within a box, so temperature should be more steady.
UPDATE on 1/16/2018:
I purchased one of these fridges from Amazon Warehouse Deals:
One of the things I liked about this one is it will go 46-66F for it ranges (so may be able to use the stock controller).
http://www.emersonra...ooler-in-black/
Unfortunately the one I got from Amazon was in really bad shape (looks like it was dropped pretty hard), it was badly deformed and couldn't even sit flat on the floor. I expected a bit of damage as acceptable (especially as I may modify it), however the price difference was only $8, so not worth it. I also was having issues with it handling temperatures to 66F at room temperature, so unsure if any internal damage, so I elected to send it back.
It wasn't a complete waste of time however, as it looks like this brand may be set up in such a way to be easy to modify. On the back of the unit there is a plastic cover that should be easy to drill through for tubing for an out world, and that has the thinnest part of the inner fridge insulation as well. I was initially thinking I would run any tubing thru the side, but it's significantly thicker on the sides due to insulation.
The back of the unit is also very accessible with a basic wiring diagram, so the peltier (TEC) controllers I was looking at could easily be modified to fit in the back. This unit also has two fans; one internal for circulation, then an on-demand larger fan on the peltier unit itself.
I ordered a 12 bottle version for my next experiment for a couple reasons:
- The increased vertical space means I can add a water reservoir to the bottom to help with humidity.
- If this experiment is a failure, it's not a wasted effort as can still use this for hibernation
Since my last post, I did find there are some companies that sell affordable TEC controller with serial control, so could pretty easy attach a NodeMCU/Arduino/etc to monitor and control it https://optlasers.co...7-15v-0-8a.html
I'll post another update when the 12 bottle version comes in next week with some internal and external pictures.
Edited by noebl1, January 16 2018 - 6:32 AM.
