Maintaining liquid cooling systems: monitor your coolant for maximum performance

Coolant is an essential part of a liquid cooling system for gaming PCs. Ensure continued high performance by understanding the ingredients in the coolant and when it is time to change.

Whether you have an AIO cooler or a unique water cooling loop for your PC, the coolant is a critical component that needs to be monitored and maintained to guarantee high performance. Even the best coolants degrade over time; the result is potential problems for elements such as plates, pumps and fittings. Consequently, to increase the lifetime of your hardware, coolant maintenance is essential.

The obvious function of the coolant is to transfer heat from the processor to reduce temperature. The properties of the liquid determine its suitability as a heat transfer fluid. Viscosity describes the efficiency of pumping the liquid. Fluids with low viscosity easily flow through the cooling system, particularly tight channels found in the cold plate assembly over the processor. Thermal conductivity is the rate at which heat moves through a material. The high thermal conductivity of the liquid promotes rapid heat dissipation from the source, in this case, the processor. The best coolants have high thermal conductivity and low viscosity. (See how Go Chiller stacks up against other coolants on the market on viscosity and thermal conductivity.)

Aside from the base fluid, additional ingredients are added to the formulation to increase the system's lifetime. These include components to maintain a stable pH (usually around pH 8), reduce microbial growth, and slow the rate of corrosion. In addition to all of these ingredients, coolants often include dyes or other particles to promote performance and provide a distinct visual impact.

Why does the coolant degrade?

Unfortunately, the coolant won't last forever, and replacement is required periodically. Certain ingredients in the formulation undergo chemical reactions to form acidic species when exposed to high temperatures and air. Most coolants have some glycol or glycerine to broaden the liquid temperature range beyond the freezing point of water, providing burst protection during transportation. Typically, the glycol is oxidised, and as a consequence, the coolant pH reduces. The metal parts of your cooling system can be sensitive to pH, particularly aluminium, where low pH induces rapid corrosion. High temperatures are unavoidable, and air in both DIY and AIO coolers increases over time due to evaporation of the coolant. Hence, regular replacement of the coolant is a necessity.

There is also a buildup of ions resulting from corrosion of metal parts of the cooling system, such as the cold plate or radiator. These ions then accelerate further corrosion. Special molecules known as corrosion inhibitors are usually added to the formulation to slow down this process. The inhibitors, though, also degrade over time and hence should be replenished.  

How often does the coolant need to be changed?

The coolant should be changed whenever you start to see a critical reduction in cooling performance. This could mean when the processor temperatures begin to increase above an average level. Other signs that it's time for replacement are visible indications of microbial growth or corrosion. However, changing the coolant at least every 12 months will prolong the lifetime of your DIY system, as the onset of degradation may not be obvious. AIO coolers have less air within the loop, and hence the coolant should last a minimum of 2 years.

Just like in your car, routine system maintenance is critical to avoid costly problems in the future. Changing your coolant at regular intervals will increase the life of your cooling components, delaying the expensive replacement of parts. Maintaining the system will also ensure that it continues to run at the highest performance level.