Holidays. How long can the reef survive?

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Hey everyone. Just looking for advice on how long a reef can go (corals and fish and inverts) without food?

I have a 33 gallon with various corals, a few small fish and the usual invert cleanup crew and crabs. I recently had some holidays so left the tank for 4 days, one feeding and then another 5 and 1/2 days before I got back. Water topoff is not a big problem since I put a tight fitting acrylic top on while away to minimize evaporation. All is well also...

Anyway, I've left freshwater tanks many times for 7 days without loosing anything, can saltwater corals, fish/inverts survive just as long? What are you're experiences?

Thanks for your help...