How to Plumb a 12V Electric Pump | Sprayer Depot, #1 for Professional Spray Equipment 

1 you should have a pvc slit filter thats inside the tank and fully submerged. That makes less connections and leak points in your intake line and also less resistance. 2 having a discharge and or a bypass line on a 12v pump won’t work if you have any type of proportioning system which is a massive part of the market and a huge selling point of 12v pumps to the market is how simple they are and easy to use because you can let off the trigger and they stop and you’re not backfilling a tank and can use a metering style system. Relays in these pumps go out because they don’t use large gauge wires and they use small junk relays. You of course don’t want draw lines super far and you don’t want to rapid cycle your pumps but if manufacturers start not allowing warranties unless you have a discharge line then they will just buy a different brand or likely kill the 12v market. Both Delavan and Remco need to step their game up on the relays they use and provide customers with a pump that has a quality relay and proper gauge wires. I have sent many emails and videos to both companies and with all things remaining the same a simple, relay and wire switch, solves all the problems. Apparently their supplier in China doesn’t have the quality they used to.