[tschmidlin]

i know my hydrometer is accurate, i always have 2 and they say the same gravity.

This doesn't mean anything if they are both wrong - are you sure you are using them right?  Proper temperatures for your measurements?  No CO2 bubbles affecting the second reading?

[majorvices]

I have 2 hydrometers, too, and they are both off, one by two the other by 4. Calibrate it to be sure, it's not hard. Just put it in room temp water and check to see it reads 1.000. Distilled is recommended, but regular water will get you close enough.

[davidgzach]

After reading the latest posts, I'm starting to think temp drop like Narvin.  However, I also agree that you need to double check all of your equipment if you have not already.

Dave