just be careful about one thing with the stealths, especially the pros... despite what this heater says about its auto shutoff feature, lately they have been dealing with a lot of returns (I am not sure if they did a recall or not) on some of them that have been exploding after being exposed to air, and then back in water, without being unplugged.
personally, I say unplug the thing anyway when doing maintenance, as a common sense best practice... but the Stealth professes it cuts off automatically when exposed to air, and that seems to not have worked so well lately... there is a thread on Simply about it... I can post it here or via PM if interested.
-Rich