Hydrometer mystery

[b0bab0ey]

I own both an Instant Ocean hydrometer and a Marine Depot refractometer.

When mixing s/w to use for WCs, I use the hydrometer to get a "rough reading" and then the refractometer to fine tune it. Well, today is a warm day where I am and the temp in my w/c drum is 84. And no matter what I do (add salt/add f/w) my sg always reads over 1.032 using my hydrometer, even though my refractometer is saying 1.016 right now. I thought maybe my hydrometer was busted so I used it to test my DT, 1.026. Double-checked my refractometer using water from the DT, 1.0264. Temp in my DT is 80.5.

So, how can this be?! I know when using a hydrometer you have to compensate for temp but this is ...... Does a hydrometer not work when the water is over a certain temp?

 

[allsps40]

Temp of water needs to be about to get a good SG reading. I never trust hydrometers.

 

[foxrazr]

Same reason that I purchased the refractometer. Can't trust a hydrometer. I threw my hydrometer away and only use the refractometer. One reason could be that you have bubbles in the hydrometer needle.... I do about 30 gallons of saltwater for my biweekly waterchange. I already know how many cups of salt to add before checking with the refractometer. Then I just fine tune after that.

 

[allsps40]

Opps I did not put in 77 degrees lol. Temp of water needs to be about 77.