water canister placement in cabinet humidor

[wgp]

For those with cabinet humidors: On what level (shelf) do you guys put your water canister in your humidor?

Mine has 3 levels, and I keep it on the top shelf, with the reasoning being that humidity falls to lower levels, but does not naturally rise. Is this bunk? In a smaller cabinet, with the circulating fans too, it might not make much of a difference, but I thought I'd ask.