This post is very helpful, and I would like to add to it. The tight lid is not only to keep it from spilling, it is to prevent evaporation, which lowers the temperature of the water. Why is water always cooler than the room it is in? Because it releases heat as it evaporates. Even with the lid on, there is still evaporation going on until the air in the jar reaches 99.9% humidity. I have experimented with a small open cup in the incubator and the temperature of the water would be several degrees below the air temperature. With the jar method, the temperature of the water begins to drop as soon as you open the lid, effecting your reading.Items needed:
1: Regular, medical type thermometer (either digital or spirit-filled) that you stick under your tongue.
2: Babyfood jar filled with water. (The lid keeps it from spilling if it gets tilted.)
Take the medical thermometer and measure some water from the faucet at around 99F degrees. Fill the babyfood jar with the water. Unless you have the incubator jam packed then you oughta be able to stick a single babyfood jar of water in there. Let it sit in the incubator for 12-24 hours along with your digital thermometer...this gives the temperature of the water *and* the digital thermometer that you want to "calibrate" a chance to stabilize.
After the time has elapsed but *before* opening the incubator, note the temperature reading on the digital thermometer that you are "calibrating". Now, open the incubator and unscrew the jar on the babyfood jar and quickly check the temperature of the water using the medical thermometer.
Compare the reading of the medical thermometer to that of the digital thermometer that you want to "calibrate". If the medical thermometer reads 99.5F and the other one reads the same then you can pretty well say the digital thermometer is reading a correct temperature. Probably, though, they will have two different readings. The medical thermometer, which should be more accurate, is your standard to measure against. If the medical thermometer reads 99.5F and the other one reads 100.2F then you know the latter one is reading too high and you need to subtract .7F from it's reading to give a more true reading....if it read 97.5F then you would then *add* two degrees to it to equal the medical thermometer. Once you figure out the difference between the two thermometers then you just have to make a "mental calibration" when you check the reading of the one left in the incubator.
Now, is that clear as mud?
Hope it helps. I do guarantee that the info is worth exactly what you paid for it.
Ed
The "water wigglers" that folks recommend work well because they do not allow for heat loss through evaporation. Here's an easy method I have found to work without having to buy anything special. Just use a digital medical thermometer and a ziplock bag. It is important to use a digital thermometer so that you get a reading to the tenth of a degree, and so that you get a reading quickly, before the water temperature changes. Put enough water in the bag so that it is about a half inch thick when zipped up and laid flat on the counter. Squeeze all the air out of the bag as you close it so there are no bubbles in the bag. Put it in the microwave for a few seconds at a time until you bring the temperature up to 99 degrees. Don't open the bag to check the temperature; just wrap the bag around the thermometer. Place the bag in the incubator on the rack where your eggs will be and leave it and the thermometer you are calibrating in the incubator for several hours. Then check the temperature again by wrapping the bag around the thermometer. Then just calibrate mentally by following the instructions in the post above.
Another note: It is always important to keep a stable room temperature and avoid bright lights. Keep the doors and air vents open in the room so that it is stabilized by your central heat and air. If the sun shines in a window in the room, cover the window well. If bright light shines into your incubator from the outside it will create a greenhouse effect and raise the temperature. Also, if you are using a homemade incubator with light bulbs for heat, the plastic bag or jar method would only work if the bag or jar is shielded from the incubator's light bulbs. This method is best performed in the dark.
Happy hatching!
