To check thermometer accuracy:
Eggseronious wrote: Get a quart of ice and crush it or use a blender make an ice water mix put the thermometer down in about 2 inches and sit for 4-5 minutes should read 32* degrees make sure its a thick slush of ice water.
Calabrating hydrometer-from Speckledhen.
1. You can calibrate a hydrometer by mixing in a bowl 1/2 cup of salt in 1/4 cup water. Actually a couple TBSP of salt moistened with water is enough.
2.Place bowl inside a zip lock baggie with your hydrometer. After at least 8 hours, your hygrometer should read 75%.
3. If it says, for example 80% you know that it is reading 5% to high and then you can make adjustments in your readings