The cooling system will not require constant refills. Once every 6 to 12 months of operation you may need to add cooling solution to the reservoir. The liquid within the reservoir should remain above the halfway point while in operation and never at the bottom of the reservoir.
Depending on the system and Cryogenics version, to refill the liquid, you may need to remove the optical drive above the reservoir. To remove the drive, you will need to remove both panels on the system and release the screws holding the optical drive in place, on both sides of the system. Once the optical drive is out, turn the system on and remove the screw caps on top of the reservoir. It is important that you have the system powered ON before uncapping the reservoir to prevent any liquid spillage and potentially damaging the system. Use a funnel or feed to pour into reservoir on the intake side (usually the left side), make sure to use the same type and brand of liquid, if you are refilling the system. After you have nearly topped off the reservoir, seal it with the screw caps and make sure that it is on tight to prevent leaks or spilling. Verify that the liquid is flowing through the system thoroughly and allow it to filter through for a short while, begin to replace the optical drive back into the system. This concludes the refilling process for the cooling systems. A video has been provided below to explain the steps a little clearer in regards to reservoir steps.
Additional liquid can be purchased from:
https://www.originpc.com/gearshop/Categories/cryogenic-liquid - Corsair coolant only
https://koolance.com/liquid-coolant-bottles - Koolance Liquid only