Matt, sorry to hear that this has happened to your new pool! That really sucks!! You are correct in thinking that sand will help protect against future trouble. Sand has very little compaction, and would have been a good idea for filling the plumbing trenches originally. The part that really sucks is that you've got to 'jack up' a section of your new deck - the patch will always show However, what's done is done and you have to do whatever it takes to fix the problem (any chance the broken lines are on the back of the spa?)

Again, I'm sorry this happened to your new pool! Get the problem fixed and do what you bought the pool for - enjoy it all summer!!

(BTW - did you ever get the 2 spa jets to bubble?)