ive had couple things go wrong on my 1st reef tank. as far as equipment goes... ive purchase some of the cheapest things i could get. an oddysea psk-75 and a 30 dollar uv sterilizer. the psk kept breaking down. and the only the thing the sterilizer did was blow massive amounts of bubbles out of the return line. scraped both of those. the air conditiong unit broke down for the 2nd floor of my house where my tank is... while i was working i called home and had my mom put a larger freezer pack in a ziplock back and put it in my sump to keep the water as cool as possible...i come home to find that the bad had blocked an overflow part in my sump and a couple gallons was soaked in the carpet.as far as live stock, ive had to replace 5 dimond gobys. the first one i had lasted the longest, however, he eventually went missing. one day i was chanign my filter sock and guess what i found....yea, true story. he was in my filter sock, no idea how. as for the rest of them i will say they dry up quickly when they're laying on your carpet. my current one is going strong and my tank is covered. and most recently i was sitting in front of my tank doing my usual water tests. i had my thumb on top of a test tube and started shaking it to mix up the calcium testing chemicals when the tube popped out to my grip and droped straight into my sump. im still praying nothing will come of it.