HerpStat 1 has 700w output and the HerpStat 2 has 900w.... 500w each channel max.

http://spyderrobotics.com/products/herpstat12.html

I would just get enough heat tape to heat both tanks and control it with the HerpStat, although it would be more better to build a small rack out of melamine and get some tubs instead of the tanks.