Whenever checking my specific gravity i always get two different numbers when using my hydrometer or when using the plastic square thing that has the needle. the hydrometer gives like 1.020 and the other thing gives 1.023?
If you are referring to the Seatest, it is temp corrected. Floating hydrometers read at 75F I believe, and must be converted.
I don't know if it would account for such a large difference however, but FWIW I use a refractometer, and my SeaTests are right on. Just keep them clean.
personally, i use the deep six. i've never compared the deep six or the seatest to refractometer but all my beasties seem to be happy and that makes me happy.
I would suggest taking a sample to your LFS and have them test it and then compare the results against your Seatest. Just make the conversion of plus or minus the required amount each time. As said, keep the tester rinsed out after each use, preferably with R/O water. HTH.
