At the core of most cryptocurrency networks are miners, the people who use specialized computer equipment to secure the cryptocurrency’s blockchain by performing mathematical equations millions of times per second. In exchange for this computing power, and the electricity it takes to run the computer, these miners are rewarded in cryptocurrency proportionate to their contribution to the network. Given the high cost of electricity in many places and the computing equipment it takes to mine, it makes sense that miners try to maximize their return in any way possible.

As detailed in a Reddit post on r/Bitcoin, Limping-Zebra managed to create a Bitcoin mining rig consisting of 36 ASICs (a specialized chip that in this case can only be used to mine Bitcoin) that are all immersed in a tank of oil.

ASICs can get extremely hot while they’re running, and if you put a bunch of them together the heat can quickly damage the chips. To address this problem, Limping-Zebra adapted an obscure cooling trick for immersion-cooled PCs and servers for their Bitcoin miners.

On each of the 36 ASICs in the tank, the fans are reversed so that cooler oil from the bottom of the tank is sucked up toward the top of the tank in a cycle meant to optimize the dispersion of heat waste away from the ASICs. This heated oil is then cooled using a plate heat exchanger that also has cool oil from a garden hose running through it. It is then run through a filter to remove particulates and pumped back into the system.

According to Limping-Zebra, the entire setup cost around $120,000—$20,000 for the vat (which includes a heat exchanger and all the necessary electronic components, including an Ethernet switch) and another $100,000 for the ASICs. The entire system uses about 50kw of power—for the sake of comparison, that’s roughly enough power for 25 average American homes. The miners have been running “since last summer and show no signs of having any issues” and generate about 1.5 bitcoins per month, according to Limping-Zebra.

“I am a big proponent of immersion cooling technologies and believe people should experiment with it to unlock unlock the full potential of this technology,” Limping-Zebra said in a Reddit post. “I hope my sharing this will motivate some people to buy a fish tank and dunk an ASIC or a GPU in there and start learning new ways of optimizing our machines.”