I like the Penn Plax Silent Air Battery pump, it has a power cord that can detect when power is cut off to turn on airpump automatically. And it is powered by a D-battery so you don't have to worry about keeping a power bank charged.
Buy an EcoFlow River 2 or 3 refurbished on ebay. These have factory warranties and work rather well. Just hook up your return pump or flow pumps (or whatever critical equipment). They come in different sizes (wattage) and can be hooked up to a solar panel(s) as well.