Most pumps like would run a fountain or even the 500 gph pond pumps do not have the power to run a single misting nozzle of the type that you would purchase for providing a fine mist for a cage. Though some of them move a lot of water, they don't do it with a whole lot of pressure which is neccessary for providing a decent mist. I've experimented with some of these other types of pumps and the best I've gotten from a misting nozzle is a continuous drip - nothing remotely approaching a mist. Your best be is still at minimum a 55 psi sprayer pump. Check the other thread lower down for the pump available from Interlink supply.
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Matt Campbell
Animal Keeper, Small Mammal/Reptile House
Lincoln Park Zoo Chicago, Illinois
Assistant Curator
Wildlife Discovery Center at Elawa Farm
Lake Forest, Illinois