Hi Kevin, im going to go ahead and advise against using barrels.. they dont offer much for a fish tank or growbed.,. and when you consider the cost ($15 - $50) they arent really the cheapest option either... and they always look like industrial waste... because,, thats what they are
look at the Tuff Tubs at Tractor Supply Co. ...some feed stores have them, and they are very reasonably priced, and they come in all shapes and sizes. they are very sturdy and made from recycled, food safe materials. ...i use them everywhere.
Getting back to the question, most any industrial operation will probably have some of the barrels out back that they are waiting to haul away. At a non-food operation they may have held things like conveyor belt soap -- not what I would consider food safe, but good enough for rain barrels. For food safe barrels, ask at factories that make food!
As an added bonus, places that have barrels to give away may also have IBC totes.
Ive heard of people finding them at Chinese restaurants that had soy sauce in them, car washes that had soap, drilling operations that had fracking grit, etc. ...call around to any one that sells the larger water tanks, some of them stock barrels.
Try a commercial bakery. They have a lot of their ingredients in them, They may be white but definitely food grade. Here in Hawaii we get them from the bakery for &15.00
If you can answer the following questions, I might be able to help you choose the proper container.
What do you plan on using the 55 Gal Barrels for ?
Are you planning on cutting them in half lengthways ?
Are you going to make use of them in the verticle position ?
Are they for overflow storage / Buffer tank or for storing water in general ?
I was looking at something similar to what Travis Hugley has designed in his barrel-ponics pamplet. Basically, his system uses a total of three barrels. One is verticle for a buffer tank, one is cut in half to make two media beds, and one is used for the fish. Although, I might try to find a large fish container, and not use a barrel for that purpose.
I'm still researching, and am open to any suggestions....
Yeah, check craigslist, ebay...Its hard to buy just a couple, most places want to sell in bulk. I've heard somewhere that Coca-Cola Bottling plants use IBC totes and barrels, maybe you could check with them.