Best Accurate Hydrometer

[dedragon]

no one said it is hard, a child can figure out any of these tests... that obviously isnt the point. The point is many have found these forms of tests inaccurate for whatever reason. Do you find a test more reliable if you have to trust in someone viewing a device in parallel? Microbubbles, physical defects forming over time, and inaccuracy are other issues as well. If following directions, i would say a refractometer has much less room for error

 

[Ocean’s Piece]

Hope you mean the tropic marin, i dont think the instant ocean has a hydrometer other than the floating arm one, those suck

I meant tropic Marin

I see this sparked a lot of controversy. I’m more on the side of accuracy over cost so I don’t mind spending 40 dollars to get another one. Reason why I don’t get the Hanna one is because I find it just makes life easier but the job of measuring salinity is already easy so I find it a little too much for me and it does stuff I can do with other alternatives. Thanks for all yalls input.

 

[Randy Holmes-Farley]

Swing arms work but just have to rinse them after using them.
And can't beat the price.

Swing arms "work", and do a decent job with temperature corrections that other hydrometers cannot, but they are sometimes simply inaccurate. it is not always a matter of washing away deposits or bubbles.

Chemistry and the Aquarium: Specific Gravity: Oh How Complicated!

This month, Randy explains and reviews specific gravity.

reefs.com

So how do these hydrometers measure up? In my tank the water was measured to be S=35 ± 0.5 by conductivity.

Using the Deep Six swing arm hydrometer I got readings of S=32.5 ± 0.5 at 81 °F and S=32 ± 0.5 at 68 °F.

Using the SeaTest I got S=34.5 ± 0.5 at 81 °F and S=34 ± 0.5 at 68 °F.

For the standard type Tropic Marin hydrometer, I got a 77 °F/77 °F specific gravity of about 1.0265 ± 0.0003 (Figure 4), which compares well to the expected value of 1.0264.

 

[WVNed]

Both accuracy and precision reflect how close a measurement is to an actual value, but accuracy reflects how close a measurement is to a known or accepted value, while precision reflects how reproducible measurements are, even if they are far from the accepted value.

A refractometer has a high degree of accuracy but low precision unless frequently calibrated.

A hydrometer with a high degree of precision once checked against a standard like a calibrated conductivity meter
is simply a better/easier tool to use.