I have a small shed, 8x7, near the house that I use as a pump/filter house for a koi pond. This building has a 7 foot deep basement made of cinder block which houses an open top settling tank, so humidity will be high. The basement and main floor have a grate between them. I was planning on having an air intake near the ceiling on the main floor and an inline fan in the basement to vent outside. Is this backwards? Do I need the intake coming into the basement and the fan exhausting from the main floor? This building has R-19 insulated walls and R-30 ceiling.