I assembled the loop below water. In my bathtub
Problem was that the nozzle I used to fill the bathtub forces air into the water. A few days later all that air had formed bubbles all around my system. Will definitely fill it with buckets next time -_-
Worst part is that I probably still have bubbles in my rad since it's not the same temp everywhere.
Watercooling is quite a hassle compared to air. But it'd be boring if it wasn't.