How much liquid is recommended inside a H80i cooler

I recently done a mod on my H80i cooler, i needed longer tubing, so i decided to cut the original ones that were also kinda rigid and put two longer tubes, i also opened the pump to clean any dirt that might be inside the copper fins, surprisingly after 3 years those were pretty clean.

Now, i have no idea how much liquid is necessary or if it matters if the cooler is full or has some space.