With some t stats you will have a 1-2 degree temp swing and thats OK, I think its very important to incubate on the cooler side. like 87-88* that way if your temps creep up on a warm day. you wont kill the eggs with excessive temperatures. something else I see alot of people doing is playing with the eggs......constantly opening the incubator up to check on them, candleing them every week. just leave them alone and let them develope and hatch.