hydrometer to refractometer

[ecomdesign]

When I first got into this hobby I thought I'd save a buck and buy a hydrometer. I always kept my SG @ 1.024. Over the weekend I picked up a refractometer and I couldn't believe how far off my SG was. It reads 1.030!!!

I will never use a hydometer again...If you are using one throw it in the garbage. I've already thrown mine out.

 

[Michael]

well i agree the refractometers are far more accurate, however if you wash the hydrometer in fresh water before and after use they can be useful, i find you may need to dunk it 2-3 times in the tank though to get a stable reading as bubbles sometimes attach to the swing arm.

 

[THE ROOK]

I finally bought a refractometer a few months ago only to find that my hydro was dead on. I do like the refractometer better, though.

Make sure your using calibration fliud to set your refractometer. The other methods seem to be inaccurate.

 

[IslandCrow]

Just remember that a refractometer can be off as well. In order for either a refractometer or a hydrometer to be truly useful, you need to calibrate it. Generally a refractometer is going to come to you better calibrated than one of the cheap hydrometers, but it's still possible for it to be significantly off.

 

[Sugar Magnolia]

http://reefkeeping.com/issues/2006-12/rhf/index.php

http://www.reefkeeping.com/issues/2004-06/rhf/index.php

 

[ecomdesign]

I looked online at calibration instructions for my refractometer and it says to use ro water or distilled water to calibrate to 0. I checked it and it was perfect. Should I still get calibration fluid?

I always took care of my hydometer. Rinsed out after use, and never dropped it. Maybe its been wrong since day one?

 

[California Crow]

I made the switch from hydrometer to refractometer a few years ago, and would never go back. I had a new in box hydrometer sitting around, though, so I opened it up and ran a little test over the weekend.

Salinity measured with refractometer (calibrated with test fluid) - 1.025

Salinity measured with swing arm hydrometer - 1.028

No way I'll ever trust a hydrometer.

CC

 

[abulgin]

<a href=showthread.php?s=&postid=14816371#post14816371 target=_blank>Originally posted</a> by ecomdesign
I looked online at calibration instructions for my refractometer and it says to use ro water or distilled water to calibrate to 0. I checked it and it was perfect. Should I still get calibration fluid?

Yes, you should calibrate it with the Pinpoint solution. Your refractometer may well be off using RO water.

 

[Dcon912]

Since I'm new to SW, I've never used a hydrometer. I bought the portable refractometer from DrsFS, and although I like it, I've had to recalibrate it often. Doesn't seem to want to stay calibrated. Using distilled water to calibrate. Going to look into the Pinpoint.

 

[abulgin]

<a href=showthread.php?s=&postid=14816938#post14816938 target=_blank>Originally posted</a> by Dcon912
Since I'm new to SW, I've never used a hydrometer. I bought the portable refractometer from DrsFS, and although I like it, I've had to recalibrate it often. Doesn't seem to want to stay calibrated. Using distilled water to calibrate. Going to look into the Pinpoint.

Sounds like yours isn't ATC (automatic temperature compensating). Ones that aren't ATC are accurate only when the ambient temp is the same as when you calibrated it. With ATC, you calibrate it once and (theoretically) it stays calibrated as temperature changes.

 

[sacremon]

I started off using a ATC refractometer, and only calibrated using RO/DI water. Not the best thing to do. Without testing with a known concentration of salt in the water, there is no good way to know how well it will report the SG of your tank water.

I splurged and bought a Pin Point salinity monitor. What my refractometer had been reported as 1.025 was really more like 1.023 according to the calibrated monitor.