DIY aquarium chiller

[tolstoy21]

Ok, so this is still in the experimental stage, so it's still a gangly bit of wires. But the below is what I have so far in terms of putting together a DIY aquarium chiller (many thanks to the internet/youtube for help!)

I have been wanting to experiment with dropping temps a tad after some of my fish spawn in order to influence sex rations. I heat my fish room, so, while can drop a heater into a tank to boost temps, I cannot do the same to lower temps a few degrees.  This is where the chiller comes in.

The setup uses a water chiller (basically a small copper block water cycles through) stacked on top of a peltier module. Functionally, the peltier module gets very hot on its bottom side and, in affect, pulls heat from it's top side. This heat is dissipated via the module sitting atop a CPU heatsink with CPU fans running.

The whole apparatus is wired to an AC to DC converting power supply, and this is wired into an inkbird. When the temperatures rise above the desired target temp, the inkbird powers on the peltiier module, the cooling fans kick in, and the water pump starts cycling water through the chiller.

So far, I have just been testing with a 5 gallon bucket. I can drop and hold that fifteen degrees lower that room temp (going to try to go lower soon), but in reality all I need to do is drop a 20 gallon tank by 2 - 5 degrees Fahrenheit.

There are a few walk throughs on how to build these on YouTube, if anyone is interested.

For now, here is my monstrosity! My next task is to make a small enclosure for it (most likely from a small tote) and tidy up the wires and conceal them in a small gang box.

Anyway, thanks for reading / looking!

 

Edited November 12, 2023 by tolstoy21

[Fish Folk]

I need this! Wow! I’m all in for it. Can you dial this back and slow down… explain each component for a complete dummy (me!). I’m not familiar with any of the components, except the inkbird. I’d like “the recipe” 100%.

[tolstoy21]

@Fish Folk Ok, I'll try to break it down a little better.

This is the water chilling block. It's quite small, 40mm x 40mm, but they come in other sizes. This is what you cycle the water through using a small pump or power head. Water goes in one side and out the other.

 

 

The thing that cools the water is the peltier module/chip (shown below). When fed power (12v dc) the bottom side of it gets very hot and has the effect of drawing heat from the top side. Since the chiller is sitting right on top of that (connected by a thin layer of conductive grease), the module also pulls heat from the water cycling through it. If I run the chiller without cycling any water through, the chiller actually will form a layer of ice crystals on top of it.

Those two components sit atop a CPU heat sink to dissipate the heat coming from the peltier module.  You can get heat sinks in all sizes, with or without fans. I chose one that already had fans with it, for simplicity sake. The peltier has a thin layer of heat conducting grease between it and the copper seat of the heat sink. In my setup I modified the CPU bracket that came with the heatsink kit so it would hold the chiller/peltier in place. I don't love that, but it's what I have for now. I'm thinking of reseating things by using conductive tape and ditching the bracket (I don't trust it's stability).

 

 

Inkbird!  Requires no introduction. If you don't like tinkering or wiring things, you can get the more traditional-looking one that has outlets, but just be sure it can both heat and cool. Those are about 2x as much as the one below and would have me plugging more things into things. I prefer to directly wire the components.

AC to DC converter / power supply.   The inkbird takes 110v AC and the fans, powerhead/pump, peltier module all take 12v DC. So you use one of these converting power supplies to connect everything (mostly following the inkbird wiring diagram). 110v AC is fed into this from the inkbird, which is plugged into a regular outlet.  The inkbird is what feeds or cuts power to the power supply. I won't go into how to wire that because it's in the ink bird manual.

 

 

That's the best run down I can do of the parts and their purpose. 

Below is a video showing a build that hopefully gives you an idea of how the parts fit together. Or if you want to cheat and take the easy path, you can buy a pre-assembled one on amazon that's pretty identical to mine--> Chiller on amazon <--  I like to tinker and learn how things fit together so I opted to make one from scratch.

Hope this kind of explains things a little bit better.

 

Edited November 13, 2023 by tolstoy21

[tolstoy21]

@Fish Folk Oh I meant to mention, if you need to drop the temp lower, I think you can use a larger water block with multiple peltiers (enough to match the size of the block).  But this would also require a large heatsink. 

Right now it seems mine has bottomed out at 59F, chilling a 5 gallon bucket of water in a 70F room. This week I'm going to run a test on a 20g aquarium. I doubt I'll ever need to go more than 3F below room temp in a real use case, but I can't say for sure yet that this current setup will work the same given a 4x larger water volume in a room running at 80F (tank water in the room normally sits at 78F).

Edited November 13, 2023 by tolstoy21

[Pokey]

Is this better for the fish compared to a fan blowing on the surface? Also, does water temperature determining gender apply to most/all fish? (And maybe frogs and crabs?🤪) Which, warmer or cooler, for each gender?

[Fish Folk]

On 11/12/2023 at 3:45 PM, tolstoy21 said:

@Fish Folk Oh I meant to mention, if you need to drop the temp lower, I think you can use a larger water block with multiple peltiers (enough to match the size of the block).  But this would also require a large heatsink. 

Right now it seems mine has bottomed out at 59F, chilling a 5 gallon bucket of water in a 70F room. This week I'm going to run a test on a 20g aquarium. I doubt I'll ever go more than 3F below room temp in a real use case, but I can't say for sure yet that this current setup will work the same given a 4x larger water volume in a room running at 80F (tank water in the room normally sits at 78F).

If there is an economic way to drop a 20 gal. 10°-F below room temperature, that would be a game changer for me, especially with Banded Darters…

[tolstoy21]

On 11/12/2023 at 3:50 PM, Fish Folk said:

If there is an economic way to drop a 20 gal. 10°-F below room temperature, that would be a game changer for me, especially with Banded Darters…

That fish looks AWESOME!

Ok so -- CHALLANGE ACCEPTED!

I'll keep tinkering with this and will let you know what I come up with. I doubt one peltier will get this 10F down in a 20G, but I'm curious to see how this scales, so I might tinker with running a larger water block/heat sink in the coming week or two. Scaling this up in size will prevent me from using an easy CPU heatsink/fan kit. But putting fans on a larger heatsink should not pose problems.

I'll also look to keep this build as inexpensive as possible.

You can get a very nice chiller from Bulk Reef Supply, but those are $$$$$$$$. I guess people in the reef world run chillers as a normal practice? That's what got me going the DIY route, I didn't want to spend $$$$$$$$ just to experiment with temps and fry.

 

Edited November 13, 2023 by tolstoy21

[tolstoy21]

On 11/12/2023 at 3:47 PM, Pokey said:

Is this better for the fish compared to a fan blowing on the surface? Also, does water temperature determining gender apply to most/all fish? (And maybe frogs and crabs?🤪) Which, warmer or cooler, for each gender?

Water temps apply to some documented species. It definitely applies to many apisto species.

I'd also like to play with this and Odessa Barbs, as I'd like to get mostly males from a spawn. I was exchanging emails with Greg Sage a while back and he mentioned someone he knew who was breeding his line of barbs and was having very consistent male-heavy spawns. Greg didn't know what the contributing factor was, but it seems to me that something environmental must have been influencing things for that person (temp/ph/hardness?).

For many apisto species temp has the largest influence on sex determination. Lower temps = more females. Higher temps = more males. Ph is also a factor, but not as influential as temp.  Lower ph tips the scales towards males, higher ph towards females. Each species of apistogramma is affected to this in different degrees, but the trend appears the same across species. The influence happens in the first month or so of life, not at birth, and it diminishes as time goes by. 

Not sure how much a fan blowing on the top of a tank will lower the water temp, but I just liked the idea of being able to dial in temps (both highs and lows). And I also like making and tinkering with things as a way of learning new concepts, hence the project.

Also, right now, my apisto spawns either come out almost all male or almost all female, and it's driving me nuts. So I'm looking to do some experiments and see if I can even out the ratio, or guarantee all males vs all females (mostly) in a given spawn. 

[tolstoy21]

 

@Fish Folk Doing some investigating last night and found out that the heat output/cooling potential of a peltier module is determined by the current (wattage) its rated for. So more wattage into the peltier = colder water. I'll be upgrading my current chip to one that draws more current this week and then will run some more tests.

There seems to be a few ways for me to increase the potential of the chips without replacing any existing hardware (other than the chip itself). However, at some point I may hit a limit of what my current power supply can push as well as what my heat sink can effectively cool. My guess (very uneducated guess) is that, for our application, I should not hit that point. I did intentionally oversize my power supply to give myself some headroom.

In the end, I'll get you that 10 degrees reduction even if I have to electrocute myself or burn down my house in the process! 

🙂

Edited November 13, 2023 by tolstoy21

[jwcarlson]

I'll be curious to know how long your peltier module lasts.  They are the technology that heated/cooled the old Reptipro incubators (RIP to that company, as they were great incubators and I think went out of business in large part to wildly inexpensive knock offs that suck).  My original Reptipro unit worked well for years for anything from chicken eggs to queen bee cells to liquifying honey and even as a dough proofing machine.  Eventually the peltier went out and tore apart the unit to figure out what the problem was, ordered another unit and that one only lasted like two uses.  

Hopefully yours run more on the longer life end!

Very good idea, though, they're very cool little modules and I was shocked (or... burned rather) by how quickly the heat up!

Forgot to add that I use quite a few of those Inkbird modules as well, they're really great units!  

Edited November 13, 2023 by jwcarlson

[tolstoy21]

@jwcarlson I'm also curious to see how long they last. At this point, I'm grabbing pretty cheap ones.

Good thing is, if they fail while in use it won't kill any fish, as the tank temp will just come up to room temp.

[tolstoy21]

@Fish Folk Ok, update time.

With my current Rube Goldberg Chilling Machine I can lower the temps in a 20 gallon aquarium by 5F, going from 74.5F to 69.5F, approximately.

Soonish, I'm going to experiment with using a larger, more efficient heat sink and running up to three peltier modules on a larger water block (a 120mm x 40mm block as compared to 40mm x 40mm). The peltiers run pretty hot (by design), so the more heat I can dissipate, then--from what I have read--the more heat I should be able to draw from the water.  Three peltier modules is about all my power supply can handle, but I think I should (finger crossed) be able to get a 10F reduction in aquarium temp. 

I did switch out water pumps after a few tests. I  opted for a small, inexpensive in-tank pump that had a variable rate so I could adjust the water flow and increase the water's contact time with the chilling block. The in-tank pump also reduced the gangliness of the set up a tad. 

I'm now also wondering if the addition of a lid (dual wall, polycarbonate) and perhaps some form of insulation on three sides of the aquarium will have a meaningful effect. I'm thinking to temporarily silicon  1" polystyrene sheets to the aquarium back and sides and see if this increases overall efficiency.  I keep my tanks oriented portrait so this shoudl significantly reduce the amount of uninsulated surfaces exposed to the ambient room heat. This will probably be somewhat unsightly, and impractical on more than 1 tank, but I think it's worth measuring the effect.

Right now my power consumption runs at about 130 watts. As I scale up, usage should increase proportionately (and so will my electric bill!). This should also have the effect of adding heat to the room (not sure if this will be by a proportional amount), but this is probably a good thing. Right now, my Frankenstein's Chiller runs continuously, but in production it shouldn't, as I don't really need to reduce my temps by that much. My goal is 2 -3F reduction for the first month after fry hatch. 

Anyway, more to come.

(If anyone is wondering why I am doing this, it's to see if I can dial in the sex ratios of an apistogramma spawn, as suggested by published research on the topic).  

Edited November 17, 2023 by tolstoy21

[jwcarlson]

On 11/17/2023 at 7:10 AM, tolstoy21 said:

(If anyone is wondering why I am doing this, it's to see if I can dial in the sex ratios of an apistogramma spawn, as suggested by published research on the topic).  

I'd assumed that you were looking into this for this exact purpose... reading the... oak leaves from your other posts.  There's suggestion of keeping spawns down at these temperatures or artificially pulling eggs and chilling them?

[Aguinaga]

Definitely be following for my axolotl tank. Thank you everyone in the thread. 

[nabokovfan87]

On 11/12/2023 at 10:30 AM, tolstoy21 said:

I do have a peltier plate sitting around... You know, things one keeps on hand.

I swear this is straight out of a Jayztwocents video (youtube overclocker guy for PC parts)