It's 48" long, by 13" wide at the end/18" at the bow center, and 23" tall. And it came with a 300 watt submersible heater from All Glass. I have a few other heaters from previous tanks we've had before.. in the 200- to 250- watt range. So yes, for anything over 50 gallons, I would use 2 heaters. It keeps the temp more consistent and if one fails (which is inevitable), the other works as a backup until I figure it out and replace it.