Only one failure and no damage from it.
I was playing a game online and suddenly my MBM5 alarm went off... I shut down the game and look at the temps... they were well above the "norm" on my machine. :shrug: I shut it down.
Opened the system and the pump was still running (separate power cord) but I had NO FLOW!
Further investigation showed that the submerged pump I was using was fine, but the hose connecting it to the "out" barb on my reservior was ruptured.
I found that the tubing I had been using (medical tubing, tan color, same stuff they use for tornequets, sp?) was deteriorating with submersion in water faster than the rest of the tubing.
It turns out that stuff is made out of almost the same compound as rubber bands (tan ones) and so was subject to the same deterioration.
Bottom line... bad planning on my part. I've had vinyl tubing ever since and have had NO problems at all.