You asked for 2 pumps, I assume to push water through 2 reactors. If you are going to use the two reactors on the same tank (one carbon and one phosban for example) you don't need two pumps. You can connect the "out" of reactor one to the "in" of rector two. Tada! one pump for two reactors.
If you were going to use these on two different tanks then nevermind.