If you have a still air incubator you want to take temps near the tops of the eggs striving for 101-102F. If you have forced air, laying on the grate or turner is fine and you want 99.5F. Many of the aquarium thermometers are light and can sit right on the eggs. The most important thing is to check whatever one you have for accuracy. I've never had the Brinsea, but I was under the impression the spot check was just that, a tool to check periodically to make sure the other thermometers were accurate and to scope out hot/cold spots rather than it being the main thermometer, but I could be wrong. I use Springfield Precision digital therms that run like $6 at our Kinneys. It's the only Springfield I'll use as I had a analog one for my first hatch and it was way off. I use an accurite digital for the humidity, but I mostly monitor air cells for that rather than depending on the hygrometer. It's just a guide for me. Many people use the repto thermometers and hygrometers that you get in the pet stores.