That's pretty chilly. Nems I'd say should be alright. Corals it heavily depends on which we're talking about. I've seen Duncan's survive things I previously thought only a mushroom could... Other corals melt when you look at them funny.
Adding any available pumps to the system (sump?) and just plugging them in would help to add a little heat. An incandescent lamp or two inside your stand should also help out, if possible. (The bigger the better for pumps and lightbulbs!)
Cover the tank (and sump) to reduce evaporation if possible.
Again if possible, divert more HVAC heat into the room where the tank is. Close the doors in the room to keep heat and humidity in. Block heat from other rooms where possible, forcing more into the aquarium room. Turn up the house thermostat a degree or two. All of these things will compound and each will help a little bit.
Good luck!
-Matt
