I used Williamson peristaltic pumps with a Korallin calcium reactor (hooked up to the outlet port, therefore pulling water from the reactor). I recently switched to a Vertex RX-C 6D and I couldn't make it work properly with the same peristaltic pumps. Neither connected to the inlet nor to the outlet. I guess they are not strong enough for this reactor. Finally I had to use a regular pump to feed the reactor. Fortunately, the needle valve of the Vertex is great for the fine adjustment of the effluent. May be if you are using a Masterflex peristaltic pump it is strong enough to do the work.