I have the dual. It works, but if I could do it again, I'd probably get single reactors. I hate trying to change one media while the other is still good. The flow can also be tricky. Part of my problem is my reactors are hard to get to under my stand, which is precisely why I'm moving my filtration to an easily accessible area in the room behind it. Something to consider with single reactors, you need a pump for each or need a manifold to feed each.