> I have a different view of where to place the pump relative to the tank. If > the pump is above the tank you are asking it to suck the contents of the > tank all of the time even at start-up. Most pumps do better at pushing than > pulling. Also, you are asking for a dry start-up every time. You're overlooking one minor little detail: his tank discharge fitting is on the top of the tank, with a pickup tube inside the tank to the bottom. So the pump has to run dry long enough to pull contents out of the top of the tank no matter where it's installed. Putting it at the top of the tank will shorten the distance that the pump has to pull the waste before it can push it overboard....AND because it will now be downhill to the thru-hull (it's an uphill run from the pump in its current location), it will also get an assist from gravity. > Most pumps do better at pushing than pulling. I haven't found that to be true except when it's downhill from the pump to its destination. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://shop.sailboatowners.com/prod.php?51996

Peggy wrote: You're overlooking one minor little detail: his tank discharge fitting is on the top of the tank, with a pickup tube inside the tank to the bottom. So the pump has to run dry long enough to pull contents out of the top of the tank no matter where it's installed. Putting it at the top of the tank will shorten the distance that the pump has to pull the waste before it can push it overboard....AND because it will now be downhill to the thru-hull (it's an uphill run from the pump in its current location), it will also get an assist from gravity. Reply: Peggy, I may have misunderstood your last paragraph. I thought that you were giving generic advice to all of us about where to locate a discharge pump. I did not think that you were still answering the question about the tank with the pickup tube on the top. My bad. You described where to locate a pump and then said: " An easy mod to do on most boats." I thought most boats had tanks with the discharge tube at the bottom. But, then I have not been on "most boats." I think that I agree with you that in his case locating the pump at the top of the tank is a better idea than at the bottom of the tank where it is now. If nothing else, when working on or replacing the pump he is certain to have liquid in it. Also, if it is high and dry as you suggest there is nothing to winterize. Have fun and keep your motor running... Eric Thoman Abyssinia