Coffee Pot Aquarium Keeps Fish Warm Without Cooking Them (hopefully)


Beta fish are one of the easiest pets to care for. So when [Derek] gave his girlfriend one for Valentine’s day he thought the job was done. Turns out these tropical pets want 75-80 F water and that’s not going to happen in a plain old bowl when you keep your home thermostat in the mid sixties during the winter. While looking for a simple heating solution he stumbled across the idea of using a cheap drip coffee maker as an aquarium.

The two main components are already in place: a clear glass vessel for the water and a way to heat it. The real trick is to use the heating element to gently warm the water to the appropriate temperature. Perhaps the key piece of the project is that the device already had a timer that shut off the heating element. This translates to easy control with his MSP430 microcontroller as it means there’s a relay present. He also patched into the two seven-segment displays to give him feedback on the temperature currently being read by the RL1003 thermistor which is submerged in the water. You’ll also note that he added a few LEDs to the lid to give the aquarium some inner glow.

36 thoughts on “Coffee Pot Aquarium Keeps Fish Warm Without Cooking Them (hopefully)

    1. Blue light will actually bring out natural colors from neon tetras that aren’t visible under full-spectrum light. It better represents the color of light deep underwater where most of the spectrum has been stripped away. I used to keep a blacklight next to my tetra tank and when they’d swim to that half of the tank, their orange and blue stripes would glow brightly.

      1. Nowhere in this article does it suggest they live in water that’s less than 5 gallons. Also, they do live in “shallow pools” of marsh and paddy, but they have an ENTIRE ACRE to roam, with many male Betta indicus [sp? wild-type, not Betta splendens] having ranges of over 100 square feet, even during the “dry” season. Taiwan doesn’t have massive water level changes like African savannah between the wet and dry season.

  1. Very sad indeed. Bettas are surface dwelling fish that can only thrive when they have sufficient surface area and tank volume, which is definitely NOT provided by a coffee pot.
    I would never try to keep one in anything less than a 10 gallon tank, and I would also include floating plants. Anything less is survival only, which is not fair to the fish. “Betta bowls” are just torture.
    As an avid aquarium enthusiast, I just can’t help but be annoyed when I see stuff like this. Like any other pet, fish have environmental needs that should be met, or they cannot thrive and will die an early and possibly painful death (how would you like to live in your own urine?). Do your research before getting a pet, people.

    1. This is absolutely correct. I started with a little fish bowl and i have upgraded to a 10 gallon tank. They need plants and company. There can be 1 male betta and 3 female bettas in the same tank, medium planted. They can also be put with non aggressive community fish, but nothing with a long billowy tail, likemollys.

      tldr; this coffee pot is putting the fish under a ton of stress. get it a bigger tank, some friends, and a decent amount of plants.

  2. [quote]…please stop torturing your fish…[/quote]

    Interesting, since there are commercially available Betta fish tanks that are the same size or smaller than the coffee pot I am using here:

    Anyway, he seems happy enough. One word or warning, though – keep cats away. I caught ours right after he had actually disconnected the temperature sensor! Luckily I was right there and caught it in time. I guess he wanted his fish cooked. I moved the tank to my shop where he is out of harms way and swimming around happily.

    1. Not to seem rude, but…

      1. Just because commercial tanks are available in that size does not mean it is not torture! Do you keep your dog on a 6′ lead? Cat in a crate?

      2. Last time I checked a gallon was 16 cups, most cheap coffee makers are for 8 or 10 cups, the largest I have seen is 12 (or 3/4 of a gallon), so 2 of your three links are for larger aquariums

      3. For fish to be less stressed (they are never truly ‘happy’ in a small aquarium) they need several things.
      Cover – Plants (even plastic), or a ‘cave’ i.e. a place to ‘chill’ and hide.
      Steady Temperature – Rising from 78-84 before falling is a problem as well. That means the rocks are heated ABOVE 84 and DEFINITELY TOO HOT for the fish to rest on (or near) Basically the fish needs to stay in the top half of the tank to be remotely comfortable.

      Lighting – for about 8-12 hours per day – much more than that puts stress on the fish.
      Aeration – steady O2 will go a long way toward reducing stress.
      Fresh Water – Water needs to be changed regularly to reduce Ammonia build up which stresses the fish.

      Sorry, but you need a MUCH smaller heater to maintain temperature, or at a minimum put the probe in the rocks at the bottom.

      Take some time to review:

    2. Yes, there are indeed commercially available betta bowls that size. You can also by unhealthy dog food and chew toys that are choking hazards. That kind of stuff is drastically less regulated than stuff for humans is.

      The problem here is that people read that betas naturally live in stagnant pools, and they think of urban/suburban puddles. That’s really not the case, but it makes folks go “hey, this is the perfect fish for someone who doesn’t want to maintain a big honking tank”.

      People also see that betta fish *can* breath from the surface, and don’t stop to think about whether that’s really best for them. Polar bears (and many other arctic critters) are adapted to go through extremely lean periods, but you’ll note that zoos don’t make their polar bears go for days without food.

      This isn’t a burn, I’m not trying to say “lrn 2 aquarium” and I’m not trying to put you down or make you look dumb on the internet. I just feel bad for your fish. :C

      You’re trying to make a better habitat, so kudos to you, but you need to do a little more research.

  3. Why not scoot the temperature sensor between the plate and bowl? Yes it will cycle more frequently but having it as a dangly wire probe is just asking for temperature run away.

    Or perhaps consider something more rigid like a metal tube-arm that has to be unscrewed from the controller side, like copper piping with a screw termination on one end.

    As for all the size comments, come on. Its going to be far happier here than inside the dixie cup jail-cell it originated from.

  4. The sensor IS in the rocks to account for the fact that the rocks hold temperature. There IS a fish in the aquarium now – has been for over a year – and he seems happy to me, so…

  5. Now we just need to find a coffee pot large enough to hold a salmon*, and a timer based coffee maker. I’d love to come home to a well timed delicious home cooked dinner… You think we could include something to automatically clarify butter?

    “Grill…. You’ll be my dinner soon….” (with nods to Urge Overkill…)

    * Hey, I’m not asking for a grouper sized pot! Yet…

  6. Others have already pointed out the ridiculously undersized tank size. I sincerely hope this has been done for the novelty factor, and the fish will be put into something less of an eyesore. Aesthetically pleasing this is not.

    However, as strange as this setup is, this is not entirely pointless, as it raises a valid question: Why are there no low-cost aquarium computers out there, to control lighting (sunset/sundown/moonlight simulations using LED strips or lamps) and heat (regular heaters, not hot plates, please!), and possibly collect other sensory data? It should be fairly easy by now, with Arduinos and whatnot. Maybe that’s a project to take on …

    1. I can tell you why there are no low cost aquarium computers out there. There are two or three basic reasons.

      1. Fairly small market.
      Most people don’t want to be consistent, and tend to a tank daily (beyond maybe feeding). They don’t want to have to test, clean, and replace probes, The basics are covered with timers and maybe a couple of stand alone device like heaters.

      2. There are a wide range of plants, fish, invertebrates and corals that all have VERY different needs for nearly every facet of a tank. Some tanks just need to monitor 1 or 2 things like ammonia level and temp, and turn on / off lights, others need a bit more and may need to monitor 10 or more aspects of the tank, Things like ph, nitrate levels, calcium, salinity… The probes for many of these things are fairly expensive, and need to be replaced often unless stored in special solutions and conditions (i.e. not in the tank all the time).

      3. This is probably the largest reason. Liability! If I buy your “Aquarium Computer” and hook it up to my $15K+ Coral Reef tank and it mis-doses, mis reads… and kills my coral I am probably going to be visiting an attorney (assuming I am not one) and I am goin gto say the reason my tank ‘tanked’ was your bleeping computer. I came home and everything was dead.

      Keeping an aquarium is part science, part art, and part instinct, I have built a quite a few aquarium-puters over the years, and had varying amounts of success. But a stuck relay, or valve can make for a really bad day, especially if you aren’t there. Typically, lately I have set them up to monitor and notify then act only on confirmation (button press) for many actions (such a evaporative fill). So that I am there when changes are made and I can see what happens (make sure the tank doesn’t overfill,

      I will say, while it is certainly not a tank I would consider, the tank is certainly a ‘novelty’ style tank. I could see value putting it in the office. I think I can say, I appreciate what the builder was doing (even if not my taste).

      There is a lot of potential for improvement in the idea. If I were to build such a thing, I would have likely kept the full height and filter assembly, and hidden a bubbler in the filter, or maybe even converted the supply tank to a small ‘refugium’. That would basically double the water volume AND provide a place for aeration and denitrification (might be too small for that, but it would be an interesting challenge), letting the water flow through the filter and ‘drip’ back into the tank. But I am all about attempting to build a self sustaining ecosystem.

      1. You make some convincing points why a full-blown, all-steering aquarium computer is tricky to build and to sell. That being said, what I miss the most are low-cost LED light controllers. You’d think a small IC, an RTC and a driver circuit would be enough to build smooth sunsets/sundowns/moonlights into otherwise already cheap LED lightings (especially when you consider freshwater nano tanks, this already makes up for a third of the tech equipment). Heaters come with cheap temperature controls already, and the other stuff I can perfectly well keep an eye on myself. But the non-availability of low-cost lighting control has bugged me for years now, if you don’t want to spend hundreds if not thousands of $ on an aquarium computer, you’re basically stuck with an blam-on-blam-off timer on your lights.

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