Hmm...

I like the multiflows ( also known as the ebb-n-grow), but the waterfarms are more forgiving. If you go w/ the multiflow, pay very close attention to the upper float switch- trust me.

If you're shipping, the waterfarms will be a lot cheaper.

Each of these systems has some flexibility in configuration, but I'd be surprised if you could fit either in less than a 6x6- so you're looking at either a 600 or a K.

Either system- remember to rinse the media during res changes, as salts will accumulate.