Soo I looked into the market for an automatic battery backup for my tank. I found options but didn't like the products or price on alot of them. Some you even had to buy their fans and others didn't even have heaters! I saw this and decided I'll just make my own and wanted to share what I made. All I did was make a wooden box, I wired an outlet to a relay that is energized when it has wall power and de-energized when there is a power outage. When it's de-energized it dissconects the outlet on the box from the wall. The battery is connected to another relay that when de-energized it connects the battery to an inverter and the inverter to the plug on the box,this turns the inverter on and connects it to the outlet. It then will keep my most important things running for another 8 hours or until power is back on. Last there is a battery tender to make sure the battery is allways fully charged. Not super complex but it works good!