REALLY COOL!!!

[doch]

Out of curiosity, not to mention a little bit of 'cover my butt' has anyone ever had any problems with inline check valves failing on their return lines? I would like to get a return line coming in around the bottom of my tank to get a good amount of flow going through my rocks, but am worried that if the power goes out the checks may fail... or even just leak through enough over say a 12 hour shift to flood my place . Somewhere along the way I have heard that checks can't be fully trusted... is this true? If so is there a brand or style that is least likely to have me end up with a very large bill? What about a redundant system of 2 in-lines?