[sphelps]

I'm not too worried about moisture, the sump will be sealed and the lighting canopy will completely seal the open top of the tank and then the canopy will be vented outside. I will also likely opt for concrete backerboard around the tank in the mechanical room side as appose to standard drywall. My concerns about building code are related to having a large body of water next to the electrical panel, I wasn't sure if this was an issue. Also if you're allowed to have an exhaust vent in the mechanical room, perhaps this can potentially cause a negative pressure situation more easily due to the location. I know you're limited to around 200cfm on other exhaust fans in the house unless you interlock, I will not be exceeding this by any means however the duty cycle will be higher than say a bathroom fan and again the proximity of furnace may also play a role. I guess what I could do is drill two holes in the side of the house and use one for exhaust and one for make up so the canopy is vented without using air from inside the house. However then I have to wonder if that will be acceptable, I know fire code limits you to so many openings on the side of the house, this particular side already has two large windows from above, a bathroom vent, cold air intake for furnace, two vents for furnace burner, vent for water heater burner, dryer vent, and exhaust vent. It already looks like Swiss cheese, could be a problem adding more vents.

As for tank size we're planning in the range of 1000 to 1500 gallons depending on the final basement layout, most likely will be approximately 10 feet long, 6 feet wide and 3 feet tall. Will be only viewable from one side.

Thanks for the input folks!