the aio has a refill port on the rad. Simply fill this but you need to angle it to minimize the air in the rad. I never fully got all the air out in the year of use. I had to refill it day i got it because of growth in the included fluid.
Anyway I used to hard tube my pc but I then started upgrading to different CPU vendors so I had to keep changing. 9900K - 10900k - 3950X - 12900K - 13900kS and at that point I stopped when i went to the 7950x3d.