I'm not familiar with the coralife RO unit. I bought a watts premier RO unit from costco (i'm cheap, what can I say) and added on a DI unit. From what I remember when I changed mine out, it wasn't the pre-filters that limited the water flow so much as it was the RO membrane unit. I bought my replacement filters through the watts on-line website, and the replacement pre-filters were all the same, with the only difference being the membrane filter section. The higher flow membrane units were obviously more expensive. they were sold as kits, so I got 2 pre-filters and a membrane unit (for a 3-stage system). If your membrane isn't that old, maybe you just need a pre-filter? I think most pre-filters can handle a pretty high flow rate. I think it's the membrane that's the limiting factor on the flow rate. hope that helps.