Hi Dino , i have just built a trolley and i only use a shurflo 35 psi pump , it is more than enough , it can deliver 3 lpm , but that is more than enough , remember your only gonna be using 25 L barrels so it would only last around 8 minutes , not enough ! , i made up a simple by pass and now i can cut the flow back to around 1.5 lpm , 15 minutes work , which is better than 8 !
Rich P @ F