EKWB predator 360 (w QDC): Do I ever need to flush system?

I purchased and installed this water block AIO on my i7-5820K, but never extended the loop to my GPU(s). I did uncouple the quick disconnects one or twice, just to see how it felt. Can I treat this as a closed AIO cooler, and never have to clean it, or must this system be flush periodically? I purchased approximately 18 months ago. Even though I've never flushed the liquid, do vacuum dust from radiator every 2-3 months.

FYI: My original intention was to sell this once EKWB discontinued the Predator line, but I noticed the new MLC line doesn't appear to have a closed loop variant. I'm not 100% sure on that last point, so please feel free to correct me. Thank you in advance.
 
Solution
I'll look into this kit to see what I can find.

EDIT: Looks like it has a premix style coolant, which is usually good for a few years before needing changed. Typically have anti algae and corrosion inhibitors in coolant. It does say in supplied documentation you can disassemble the kit, including drain and fill with fresh coolant if you like. This is from a review I found. Very user friendly AIO, almost to point of being custom.
I'll look into this kit to see what I can find.

EDIT: Looks like it has a premix style coolant, which is usually good for a few years before needing changed. Typically have anti algae and corrosion inhibitors in coolant. It does say in supplied documentation you can disassemble the kit, including drain and fill with fresh coolant if you like. This is from a review I found. Very user friendly AIO, almost to point of being custom.
 
Solution