The prizms aren't that great I had one for a very short while, even my LFS didn't care for it they had three of them sitting in the back room because they were tired of messing with them and pulled them off of there DT. I could never get mine to skim consistantly it would work fine for a week or two and then nothing so I would adjust it and it would work again for a couple of weeks and it was a cycle like that for about 3 months and then I bought a new skimmer.
Take a look at the AqauC remora, they have been catching some flack on here lateley but I just finished helping setup a tank for another local reefer and installed an urchin which is just an in sump version of the remora. It seems to be working good and was only slightly noisy for the first week it was installed. Another local guy has one also and is extremely happy with it.