2 NextReef MR1's feed by 1 pump questions?

[The Grizz]

So I now have 2 MR1's, 1 is running Vertex pellets feed by a OR 2500 pump. The 2nd is going to be for ROX. My thought is to run them off the same pump into 1st reactor, then 2nd and return out to skimmer intake.

What should come 1st, carbon or pellets. My thoughts on this would be carbon 1st because of the mulm that comes off the pellets would plug up the carbon & foam pads in the reactor.

Am I on the right track here or do I need another pump for the carbon?