I have a Intex pool with the 2500gph intex pump, SWG and a 200# sand filter. (I just removed the cartridge from the intex) I hooked it up by cutting the cheesy white flex hose off right behind the flat part of the connection. Then you can go to Home Depot and get the 1 1/2 rubber couplings that have a hose clamp on each end and adapt straight to PVC. From there, you can plumb anything you want.

I am having problems getting the Intex pump to run a robot sufficiently, so I may be upgrading the pump soon, but as for adding the sand filter to the intex, I would NEVER RUN WITHOUT IT! Its the best thing I have ever done for my pool. (And my nerves!)