I've been thinking for several weeks how to best set up a bait tank on my pontoon boat that would keep herring alive. After numerous designs and attempts to make a good tank I think i have FINALLY came up with the perfect bait tank. Let me know if you guys think this will work.... I have one of those big white coleman coolers, i think it's 120qt or 144qt. It has rounded sides, this is what I will be using for the tank. I plan on positioning the tank long ways up against the side rail of my pontoon. The drain hole will have pvc pipe leading to a self priming pump which will rest on the top of my left tube, just under the deck of my boat(there's a good place to position a pump in this area and it wont be taking up my fishing space on the deck, Anyways, the pvc pipe from the drain hole will go to a Tee fitting with a shut off valve placed before the pvc pipe reaches the junction. The other side of this junction will have a pipe which drops off the side of the tube and below the water level water level to draw in water. This pipe will also have a shut off valve. THe Tee fitting will lead to the input of the self priming pump. The output of the pump will go along the pontoon tube for a short distance so an enclosed filter of some type can be held in place here. From the filter the pipe will then come up through the floor and into the top of the tank where a spray nozzle will shoot the water into the tank. Now, with this system I will be able to easily drain my tank by opening both shutoff valves on the intake. Also, I will be able to recirculate water without bringing in lake water by closing the shut off valve to the fresh lake water input and opening the shutoff valve coming from the drain hole of the bait tank. I want to accomplish this so that in the hot summer time I will be able to have a closed system so I can control the water temperature. Problems: One problem is that I am not exactly sure how I can connect a filter unit onto my system. They dont really make anything from pvc pipe that you can fill up with filter material/charcoal. I would like to find some kind of water proof box that has 2 connections for 3/4 inch pvc, but this box would need to have some kind of a way of getting in it to clean out the filter. Secondly, I am not sure if a water pump will be able to deliver enough power to do what I want it to. Does anybody on here have an idea of a good way to connect a filter into my water line that won't leak, but will allow me to open it up and clean it out? So what do yall think about this idea? Am I wasting my time or do you think this could be viable bait tank for keepig herring alive in the summer? What other problems do you think I might encounter? Thanks for your input!