How much of a temperature gradient do you guys see in your incubators? Even with a 4" computer fan running in my wine cooler incubator, I am seeing about a 2.5 degree range in temp from the top shelf to the bottom shelf. When the top shelf is at 90 degrees, the bottom is at about 87.5 degrees. It does stay very stable though. Will this hurt anything? Maybe the bottom will just take longer to incubate?

Thanks!