Galvanic Corrosion in Watercooling

Galvanic Corrosion in Watercooling

Galvanic corrosion is the single biggest killer of custom water cooling loops, and it is completely preventable. It happens when two different metals are in contact with each other in the presence of a conductive liquid, which is exactly what happens inside a water cooling loop. The more reactive metal corrodes rapidly, shedding particles that can clog your water block and damage your pump.

The science is simple. Different metals have different electrochemical potentials. When they are connected by a conductive liquid, they form a battery. Electrons flow from the more reactive metal, called the anode, to the less reactive metal, called the cathode. The anode dissolves over time. In a water cooling loop, this means your aluminum radiator will slowly eat itself if you mix it with copper water blocks.

This is why you should never mix aluminum and copper in the same loop. Aluminum is highly reactive, and copper is relatively noble. If you have a copper water block and an aluminum radiator, the radiator will corrode and fail. The corrosion products, white powdery aluminum oxide, will circulate through your loop and clog the fine fins inside your water block, destroying its cooling performance.

The safe combination is copper and brass. Brass is an alloy of copper and zinc, and it has a similar electrochemical potential to pure copper. This means they do not create a significant galvanic reaction. Most high-quality water blocks have a copper base, and most fittings are brass. Radiators are also usually copper or brass. Stick to these materials and you will have no corrosion issues.

Coolant also matters. Distilled water is not conductive, but it becomes conductive as soon as it picks up ions from the metals in your loop. This is why you should use a coolant with corrosion inhibitors. Many coolants also include a biocide to prevent algae and bacterial growth, which can also clog your loop. Change your coolant every year to keep the inhibitors effective and your loop running smoothly.