I bought two of these from LA to replace my old-school 2xD-Cell battery air pumps. Unfortunately, not only can I not make the Cobalt Aquatics Rescue Air DC Air Pump consistently work per the instructions with the provided additional USB power brick, sometimes they won't go into "fail-over only" mode at all. Worst of all, the face of the AC adapter (the part that plugs into the wall) separates easily from the body of the AC/USB adapter leaving two "hot" powered prongs sticking out of the outlet. This happened on both of the units I bought.

I purchased one of these "just in case" after watching the LiveAquaria video last summer. After a 42-hour power outage from a freak winter storm, I'm convinced this is the best investment I ever made in aquarium equipment. The pump chugged along nicely the whole time. I used the USB battery to recharge it on the fly, just to be sure it didn't run down, and I had enough spare juice to charge my iPhone too. All indications are the 72-hour run time is real. It can comfortably run one large airstone or one sponge filter in a 55-gallon tank (I was concerned about depth, but no problem). After power came back, we had rolling blackouts for another day, and the unit kept running as the power came in and out, switching from plug to battery power. The 10-second pulse mode is handier than I thought when you're worried about stretching the run time. The battery indicator light lets you know how much charge you've got at any point. I had a second, cheaper pump that I had to recharge and check repeatedly, while this unit was a breeze. Really impressed and happy with the quality of this product.