Im assuming you have zero experience with construction or renovations???
300 gallons is a ton of water, fresh or salt doesnt matter your flooring will be ruined your drywall, baseboards, paint, insulation let alone any of your personal things the list goes on and on. in a sealed house how exactly do you think this water will pour outside doing little to no damage if it blows while your at work?
i have no idea how you could even sleep with that in the house.
I couldn't but Im not willing to be 20,30,40 grand on a bowing tank that a new one eurobraced that wont bow is what? $1000-1500??????
if you decide to keep it Id delete this thread if your insurance finds it basically stating you thought there was a problem you knew it was bowing but some random dude on another forum told you it was fine good luck seeing a dime.