6 months would be fine. Every 3 months too much? As distilled water is so cheap. The thing that is most impressive in the loop is the fancy drain port. Lobe how it slides back and forty with a click rather than using a tap/ball valve. I'm going to keep the loop clear to match the two tone black/chrome. While giving a bit of RGB sparkle from the distro plate, memory and graphics block. I keep reading about stories of people using something in their loop to lubricate the pump. Then I read others to stay away from silver coil as it says that will void EK's warranty and cause flaking.