When I was building my pond, I was going through a lot of fuel. I found a beat up trailer for super cheap, and a couple of 100 gallon aluminum fuel tanks from semi trucks that had been damaged for next to nothing. I bought a Tractor Supply fuel pump that worked OK, but didn't last very long, so I replaced it with a Northern Tool pump that has worked out well. The fuel filter is from Napa and it has a replicable cartridge that works great.
I cut some boards to create a cradle and I used some metal straps to bolt it into place. I bought a fuel lid from Summit Racing for the tank I use to fill it, and I had a welding shop weld on an aluminum nipple that fit the threads of the electric pump.
I power it from a cigarette lighter plug that I put on all my tractors.
There are two hoses at the bottom of each tank that connect to each other. One is bigger then the other. I just put a fuel line on the existing nipples at the bottom of the tanks so the fuel will flow from the tank that I'm filling, and go into the tank with the fuel pump. Filling starts out pretty fast for the first 150 gallons, but then it gets slower and slower. I put a water spicket on the pump side tank to let air out as the fuel fills up the tank and that helped, but it's still slow getting the fuel to go to the other tank once it gets to a certain point. If I spend the time, I can get 180 gallons, but I've never been able to get much more then that. If I was going through a lot of fuel and filling it a couple times a week, I would usually stop at around 160 gallons or so.
Since finishing the pond 15 years ago, I've only filled it a few times. It's not really worth the time it takes to go to the place that sells Farm Diesel. I same around .30cents a gallon with Farm Diesel, but it's an hour drive to get there, an hour to fill it up, and an hour to get home. Plus the time it takes to just make it all happen. Now I just use 5 gallon yellow cans and fill up two or four at a time and that's proven to be plenty of fuel for what I do. I should sell it, but it's out of the way and not something I've thought about in awhile.