I don't leaktest for 24 hours...I generally do it for 2-3 hours, although I have done it for 24 before.
As far as maintenance goes, the only thing you need to do is change your water approx every 6 months assuming you've set your loop up right the first time.
This is why a test PSU comes in handy, so you can turn on the pump and get water going through your loop without turning on the computer.
I remember I had set it up, used the test PSU to leaktest it, and sure enough after a few minutes water leaked from one of the CPU barbs onto the back of the video card and then one of the video cards barbs leaked too landing on the back of my sound card.
Cleaned it up with some 99% isopropyl alcohol, made sure it was dry, redid my loop...no leaks and it didn't leak after that and the system still ran.