Well, you have to realize that there are 12 (+-) staff in Camp Carnival(there were 12 pictures posted as Camp staff on our ship - but who knows how many were actually on the ship on that cruise), and it depends on how much time your kids spent in it, plus the time camp is closed. The older they are, the less time they want to spend in there. My 10 year old spent maybe 10 hrs in there all week. The 7 year old spent maybe 15-20 hours, the 2 year old the most.
You should probably wait til you see how much your child(ren) use it before you decide on tipping. Again, they are paid on a more salaried basis than the wait-staff, who work for tips.