refugium and skimmer question

[mxpro32]

   i am setting up a tank for my girlfriend. its a 10 gallon with a 5 gallon refugium.  im planning on putting miracle mud with some caulerpa in the refugium. and maybe some sponges.  (a guy at my lfs said one of his customers uses a sump with a bunch of sponges as his only filtration)  i am also planning on running a skimmer(probably a prism)  i am just wondering if you can go longer without water changes if you are running a skimmer and a refugium?

[Fant]

Combining an effecient skimmer with a refugium has never worked for me. If its a good quality skimmer, im not sure about the prism, it will eventually outcompete the caulerpa in the refuge, which would then stop growing and be pointless. As to water change volume and frequency that all depends on the stocking and feeding of the tank. If she wants a low maintainence easy tank, then dont add any fish just stock it with a few light loving soft corals. If she wants fish then she needs to be ready to commit to the maintainence required.