don't let this happen to you
Sorry to bump this one up, but a fellow member just had a near disaster that could have been prevented if it wasn't for some simple mistakes.
First, if you are going away on vacation, let members of MR who live close by know that you are going away so they can check up on your tank for you. There are many members here willing to do this. Check the Sticky for emergency help posted in this forum. Leave any family members or house sitters with contact information if there are any problems. In this case, the house sitters know nothing about tanks. They were unable to contact him last night while he's away. They didn't know how to contact us. They finally got a hold of him this afternoon and we went over to fix the problem. This was close to 24 hours after the family members FIRST NOTICED water on the floor. 24 hours of more water pouring on the floor!!!
Second, if you are one of those guys who keeps a waste line running from your skimmer's collection cup to an external bucket, let me HIGHLY suggest that you spend the extra money (don't cheap out... advice already given on this thread) and buy the waste collection cups which automatically shut off air to the skimmer when the collection cup is full. This entire problem started when his skimmer went nuts, filled the 5 gallon bucket he had the waste line ran to and the bucket began to overflow.
Third, your sump should be able to handle tank water without overflowing in case of pump/power failure (again, this was already stated on this thread). Once the skimmer dumped too much water, the return pump burned out. His sump still overflowed from the excess water even after his skimmer bucket dumped over 5 gallons of water. There was water EVERYWHERE!!! If you can't get a bigger sump, you can drill siphon holes into your return to prevent siphoning. But a bigger sump is still the best bet.
Third, if you are going away and you did not take necessary precautions with a skimmer ran to an external collection bucket, either shut the skimmer off completely and run polypads/carbon or set your skimmers to skim dry. He set his to skim wet while he was away.
Fourth, Have some RO/DI made before you leave. Some mixed salt water would help too. He lost around 50 gallons of water and had ZERO RO/DI or MIXED SALT WATER! We all know how slow RO/DI fills up usable water. Conditioned tap water would do, but if given the choice, I'll take purified water.
Dave (spykes), Ronen(deepwater), Rich(jackson6745) and I went over today after he called us. We fixed the problems, but he lost some coral and has 50 gallons of water on his floor. Let people know you are going away. We will help you.