Hydrometer Calibration Help

[Waterbury Guy]

I have a floating glass hydrometer/thermometer. There is a small green "safe" zone that the SG should be in. It almost always reads on the low side (1.20-1.22), but is calibrated for 75 degrees. I run my tank at 80-82 degrees. Any idea how this affects the reading?

[Spanky]

Probably the easiest way to tell is to take a glass that's big enough to float the hydrometer and fill it with RO/DI water the same temp as your tank water. Spin the hydrometer to get any air bubbles off. It should read 1000 sg.

HTH
Jerel

[chewie]

Hey Spanky,

You don't suppose that would work with a swing arm type hydrometer..... would it?

[MontanaRocknReefer]

Hey chewie! I have one of those swing arm as well and I make sure it is very clean before using it to test salinity! I need to get serious and buy a Refractometer which is very accurate! A little spendy but members have seen them for around $65. Johnny

[Spanky]

You know you can calibrate any of them if you have a control. For all practical purposes, there's very few times that you need to know exact salinities/sg. The most important thing is consistency.

[Hommeworks]

I have one of those floating glass hydrometers also. I also have a book called Natural Reef Aquariums by John Tullock. In his book he has a table for measuring salinity across multiple temperatures. I keep my tank about 79 degress so I calibrate from his table for salinity ranges at that temperature.

[chewie]

Actually i quit using that darn swing arm after testing against a new one.

The new one read 1.025 and mine read 1.028, I'm holding off for a refractometer, but till then I'll try Jerel's Idea to see if my swing arm is even close.

I'll be keeping my salinity constant at 1.028

[R1Bill]

Waterbury Guy,

Check out my link:

http://www.thereeftank.com/forums/sh...threadid=10820

It has a table you can use to convert for temperature. Also, you want to check your Hydrometer for accuracy. It should read 1.000 with DI water, no salt at the calibration temperature.

Let me know if you need more help



Bill