There are a couple of choices for large batch generators that I know of. Silvergen.com makes one that will do 5 gallons at a time and has auto shutoff at 10ppm. The other one is a no-frills unit made by Terry Chamberlain (I have one) designed to work with ten 1 gallon jars so it makes 10 gallons. There is no auto shut off on his unit. Just an on off switch and a fuse (comes with silver rods as well). You can buy a ppm meter from Silvergen.com or Silverpuppy.com for $55.
Terry's unit is $400. If you have the $$$ the Silvergen is definately worth the extra money for covenience sake and auto features. If budget and 10 gallons at a
time is a big deal Terry's unit will definately make a ton of CS for low $$$. Great for a farm operation. Here is Terry's info if you need it.
Nova Scotia, Canada