Tbh richy, I only have a 350 litre tank in my van, I also have 10 barrels, again using the Merlin on the job just keeps topping your tank up with the barrels. On a job am on ATM I start off with a full tank, and a barrel fills up every 21 mins at 12 tds. By the time I am near empty I have quite a few barrels full.
I will try an put a pic up.