I did just find a site that said that Oceanic was bought a while back (didn't say when) by AGA so they are subdivisions of the same company. As for the difference in the 29 and 30 gallon cubes, it would probably be a minimal difference in dimensions. A 19x19x19 would actually be 29.69 gallons. To give an idea of how a small change makes a big difference, if you change that to 19.5x19.5x19.5 (add 1/2" to each dimension), it changes to 32.09 gallon, adding almost 2.5 gallon. I would say the 30 gallon cube would be right at the 19 square.