I looked at the tanks that had been made, I used an old ice chest for a while, then after seeing what had been done, I came up with this one for near little $. I started out with a used liquid cattle feed tub, heavy plastic. I cut it down some to save some space in the boat. It's 20 1/2" in diameter and I cut it right at 14" deep. It fit down inside the bottom of a plastic 55 gallon drum that I cut off at the 25 gallon mark. It left about 1 1/2" between them for insulation. For the areation in the tank, I used a 360 GPH bilge pump that I drilled a 1/4" hole in the center of the mounting plate. I put a 90 degree fitting used for drip irrigation in the hole. The has to be centered at impeller of the pump, but not touching it. I ran a 1/4" hose out with power cord to draw air into the pump. Just used a simple plywood to with a big door cut in it. I did add a small license plate light on the inside in case I wanted to fish at night. This holds about 20-25 gallons of water and the pump circulates the water as well as adding bubbles to the water. It took 2 cans of expanding foam insulation to fill the space between the 2 containers. Once it expanded and cured, I just trimmed off the excess with a old kitchen knife. I don't use a lot of live bait, but this thing kept threadfin shad going for over 4 hours a couple of weeks ago. To me that was a major accomplishment.