I just installed a 90 gallon tank on my 2003 2520 DV Sport Cabin located in southern California. I installed a Jabasco 50840 Series Low Pressure Cyclone Centrifugal pump 29.7 gpm in the bilge. A 1" seacock through the bottom of the boat with a clam shell opening feeds the pump. On the output side of the bait pump is a T that runs to a Jabsco Hotshot Series 12V Automatic High Pressure Washdown Pump (pump doesn't require a prime) mounted in the transom above the bilge and water line and near the starboard battery. I have found that I need to run the washdown pump to prime my bait pump. I keep my boat on a trailer so the system drains every time I pull the boat out of the water. I haven't tried to get the bait pump to prime by just running at speed (have to leave the harbor to run over 5 mph and then come back in to get bait in the harbor) assuming the water would get forced into the pump through the clam shell fitting on the seacock. I have a Groco strainer on the inlet to the bait pump and routinely remove eel grass from the strainer which I believe would damage the pump if not strained out. Highly recommend installing a strainer. I have a valve after the T to the washdown pump which allows me to isolate the bait pump by closing it and the valve on the seacock. I carry a spare bait pump. I still need to change the electrical connectors to plugs to facilitate changing out the pump.
I installed my bait tank over the pie opening to the fuel tank right behind the pilothouse door. I ran the supply (1") and exit (1.5") lines from the bottom of the bait tank, through the pie hole, over the top of the fuel tank, and drilled two holes in the top of the bulkhead wall in the bilge (FYI, this "bulkhead" was only about 1/4"+ thick and was not "sealed" to the bottom of the deck so if water filled the bilge it could get beyond the bulkhead into the area where the gas tank is regardless of whether I drilled holes through it) for the 1" line to the pump and 1-1/2" exit line through the transom. I couldn't figure out an easy way for the exit to go out the side above the water line (if I remember correctly the deck is close to the water line so the line would have to be run above the deck) and based on the research I did it is ok to run the exit below the water line. I have a flotation bracket on the transom for the engines so my exit is through the transom about 6 inches above the bottom of the bilge to stay below the bottom of the flotation bracket. I have a 1-1/2" seacock with valve for the exit. I ended up needing the longer seacock due to the thickness of the transom. Make sure you use good all stainless hose clamps (they are expensive but worth it in my opinion) and use two clamps at each connection. I used like materials for all my fittings (bronze for the pump, T, and hose barbs and plastic for the strainer). In hind sight, I may have gone with the more expensive strainer with metal fittings to eliminate plastic fittings in the bilge.
