What are the MUST HAVES for equipment?

[lockrookie]

spare parts one must have a backup plan if somethng quits so that your not freaking out and purchasing higher cost stuff in a pinch i try to keep a spare return pump spare powerheads and spare lights just in case. in 3 years i have had one of everything break on me mostly from user error. but some from just bad luck. im not saying hae a complete tank ready to go. but essentials are good to have laying around.