Aqua Clears are good PH's. I prefer the Maxi Jets, but if you already have the AQ's, use them by all means. As long as you keep them clean, they'll last a long, long time. Usually, when the impeller fails, the magnet will come loose on the impeller shaft or the impeller will break. It's good to pull the rubber tips off the shaft once in a while and clean the buildup off the shaft as this can lock the impeller down and cause the PH to overheat.
I wouldn't use a sponge on them. Aqua Clear makes a PH prefilter that will snap right on the PH. Take the filter floss out and just use it as a screen to prevent fish/inverts from being sucked in.
I think if you set up a nano, you'll find that the AQ's take up too much room. In a nano, I'd go with Aquarium Systems Mini Jets. They are adjustable flow and are small enough to fit in a 10 without taking up half the tank. They're also fairly cheap