Originally Posted by Bob in Mb
You would be best to install either a directional valve or a simple on -off valve in each line . Without a positive isolation when using the manual pump you will likely lose suction through the electric pump.
Thanks that is the plan. Planning on having a directional "Y" valve on the hose exiting the tank and then a shut off valve on the line feeding the pump and the line feeding the manual handpump. The valve to the handpump will stay closed unless I lose power and need to use it. Then I can close the valve to the 12 volt and maintain suction. But not sure if I should put the valve before or after the 12 volt, (probably before).
If it works, great. If not I will buy an electrical
pump to replace the manual I now have.