Add or Subtract Hydrometer Calibration

do you add or sub depending on the temp. IO hydrometer. i thought it was subtract but a buddy has the saltwater dummies book and he says that you have to add .01 every 10 degrees. whos the dummy?

 

Look for a refractmeter with ATC. Hydrometers are not that accurate that I would worry about .01 really it's more important to be consistent as long as you are close.

 

Sound like the book for dummies is incorrect. Niiiiiiccccce. For every ten degrees above sixty, you subtract .01 from your reading. So at 80 degrees, a reading of 1.028 is actually 1.026.

 

anyone else want to put there 2 cents in?

 

I got one of the refractometer/ electronic PH meters from ebay. I love it.
Salinity Refractometer + digital pH Meter Aquarium b - eBay (item 330287341647 end time Nov-24-08 05:43:10 PST)
As far as your question... sorry I don't know. My hydrometer I just didnt' trust..seems like I could never completely shake off all the bubbles on the needle.

 

My deepsix hydometer is way off, that's why I'll be buying a refractometer soon.

 

Honestly, I had an instant ocean hydrometer and it wasn't that bad. I now have a refractometer and I had about the same readings as with the hyrdrometer. The key is to make sure no bubbles are left on the arm. Also, I thought they were already calibrated for temp. at 78F?