Is it an Optima Dry cell or another type. It's hard to tell but the best place to start would be the manufactuers website and see if they have a chart for the discharge rate.
Maybe you could hook up a trickle charger/battery tender each night or once a week to keep the battery at optimum charge since it's not hook up to an alternator.
In any case I do not think a brand new battery would die in a day or two just running that pump.
