What is the difference between hydroponics and Barrelponics? Really, there is no difference. In fact they are the same thing. The only thing that makes them different is the name Barrelponics which was coined by Travis Hughey in 2005.
Essentially, Barrelponics uses what could probably be considered as the least expensive materials one could obtain to build the finished system. To start with Travis recommends using 55 gallon plastic drums for all of the water containment in the system. As long as you have a source for these, they are a great choice for someone wanting to build a hydroponics system cheap. The only thing you really need to be sure of is whether or not the plastic barrels are going to be food safe. It would be a shame to build one of these out of plastic barrels that essentially leech toxins into your system.
Where can you find plastic barrels suitable for a Barrelponics system? The first place to start would be any company that deal directly with packaging food. Consider a ketchup manufacturing company for example. They may very well use plastic barrels of vinegar as part of their processing. Another great source might be a winery or an olive packaging company.
All in all Travis has assembled a working system. If you take a look at the Barrelponics PDF file Travis gives away as instructions for building a system like his, there are some things you can do to modify your own system. Basically all of the plumbing would stay the same, but you could dress up the system by making wooden containers much like Kijani Grows makes.
Not everyone might like the aesthetics of plastic barrels as a hydroponics system which is why using wood for the grow boxes might actually be a more pleasing look. The outside could be stained and lacquered while the inside could be waterproofed with a coating like Pond Shield.
While Travis’ system essentially is controlled by what appears to be a more mechanical means using floats and valves that are assembled to work with one another based off of the current state of the system itself, a system like those built by Kijani Grows utilize a more computerized way of maintenance. Either will work. You would just have to decide at the start which way you would like to go with your system.
The final thing that I did notice between the Barrelponics system and the Kijani Grows system is that the Kijani Grows system seems a little less complicated in the end. If you take a look at the materials list for each system Kijani Grows system just uses less material to construct. Because of this, it very well may be cheaper to put together in the end.