Greenhouse Pond Pros/Cons?
Today I ordered a 16' Rion Greenhouse 40Series. I'm in Durango, Colorado (zone 5b) and we get about 300 days of sun a year. But nights can get really chilly (-10 in winter, high 30's spring, mid 40's summer). I've been reading about how to heat this thing, and see that using bricks and water as heat sinks is a popular thing to do. I'm thinking of building my shelf bases out of cinder blocks and painting them black. And I love the idea of having a pond in the greenhouse- the whole concept of pond=heat sink, fish produce waste to water the plants with, etc... But is this a feasible idea? I know I'll still have to supplement with a heater (I've been told 30,000 btu), but are there any particular advantages/disadvantages of installing a pond? If it's a good idea to install one, any idea of how many gallons it should be to be the most efficient?