I love the running water concept to attract Chams, but would seriously consider a modification to make the pump and reservoir an outside the cage design to facilitate changes and cleaning. I would still need to get the leaves and such hand cleaned, but I hate dealing with filters and pumps. (It's like having fish for pets

) Maybe on a timer. The noise of it on could trigger a learned reaction to tell him it's drinking time..
Using only distilled water may also help.
If I decide to get a new Cham, I'm not counting on having him trained to drink out of a rodent water bottle.