Make sure a responsible adult watches your tank. I left mine in charge with a neighbor who thought it would be a perfect opportunity to teach his girlfriend's son some responsibility. The 8 year old ignored all instructions and I came home to a tank with an empty sump, return pump running dry, corals looking bad, and a cat box overflowing with crap. My cat is an outdoor cat and the box was only there for emergency, so the kid never let the cat out.
I replaced the 20 gallons and luckily had no losses. Everything looked like hell for a few weeks, though.