One of my loops is very slowly losing fluid. The fluid in the reservoir has been steadily dropping by 2-3mm per day for the last two weeks. I use UV reactive fluid specifically so I can spot leaks more easily, and yet I can't find anything when I shine my light all over. Yesterday, I went through and loosened and retightened every single connection. Today, the level is down again. WTF is going on? I even put a piece of masking tape on the res yesterday to mark the starting level and verify once and for all that this isn't just in my head.