here you go sir. best ever deep cycle battery is a blue top Optima D34. looks like a staggered 6 pack of beer. this little bad boy will provide you with the most power you could imagine. price is around $250. you can also run household stuff like phone chargers and flashlights. the difference between an optima other batteries is the number ot cycles. i went to school for both car stereo installation and design, and fisheries ( lambo's, porche, other exotics). and salmon lol. a single GOOD deep cycle battery can protect your fish tank for weeks! have an emergency heater and a smaller return pump. a single MP10 draws little power. a single optima deep cycle will keep you safe for years. a 50W heater and 4 circ pumps may draw about 75 watts. that can run for up to 5 days with little draw from your emergency system. the average D34 optima has a 750 amp reserve. thats 12 voltsx75 amps, which = 900 watts for many moons.