Hydrometer vs. Refractometer

Acroholic · Jun 4, 2009

I have a TropicMarin hydrometer, about 12" long, and measures to 4 decimal places. Supposed to be lab grade, but I use a refractometer.

One thing we learned recently is that calibrating with distilled/RODI water can skew the actual SG by several thousandths. I recently started using Pinpoint 1.0264 (35 ppt) calibration solution and found my SG was at 1.021-22 instead of the 1.026 I thought it was. After Pinpoint calibration I put some distilled water on the refractometer and it actually read below zero.
Dave

cloakerpoked · Jun 4, 2009

Acroholic said:
I have a TropicMarin hydrometer, about 12" long, and measures to 4 decimal places. Supposed to be lab grade, but I use a refractometer.

One thing we learned recently is that calibrating with distilled/RODI water can skew the actual SG by several thousandths. I recently started using Pinpoint 1.0264 (35 ppt) calibration solution and found my SG was at 1.021-22 instead of the 1.026 I thought it was. After Pinpoint calibration I put some distilled water on the refractometer and it actually read below zero.
Dave

Hmmmmm...so it really looks like both are prone to error if special care isn't taken to limit mistakes.

DaveA · Jun 4, 2009

I would like to find a scientific article comparing the two. I have heard these arguments before, viz. "my hygrometer is .004 off," but I am not convinced that it isn't the refractometer that is off. How do you know which is off? You might have miscalibrated the refractometer.

Robthorn · Jun 4, 2009

Refractometer and anyone but sybon. Had to calibrate that piece of junk everytime I used it. I have checked my new cheap one several times and has not needed adjustment in almost 3 months.

JR's Reef · Jun 4, 2009

Its all in what you trust and I trust my Refractometer more than the old swing arm.

cloakerpoked · Jun 4, 2009

Joey08 said:
Its all in what you trust and I trust my Refractometer more than the old swing arm.

And you, sir, are clearly in the majority.

Paul_N · Jun 4, 2009

Chrissy said:
What brand hydrometer do you use?

I use a Coralife Deep Six

Paul_N · Jun 4, 2009

Acroholic said:
I have a TropicMarin hydrometer, about 12" long, and measures to 4 decimal places. Supposed to be lab grade, but I use a refractometer.

One thing we learned recently is that calibrating with distilled/RODI water can skew the actual SG by several thousandths. I recently started using Pinpoint 1.0264 (35 ppt) calibration solution and found my SG was at 1.021-22 instead of the 1.026 I thought it was. After Pinpoint calibration I put some distilled water on the refractometer and it actually read below zero.
Dave

I use Randy's DIY calibration solution. I also checked it against Pinpoint.

Pablo · Jun 8, 2009

I use a hydrometer but I want to buy a refractometer.

brandyrb · Jun 8, 2009

Refractometer. I don't trust hydrometers.

scrapz · Jun 9, 2009

IMO a calibrated hydrometer(by refract) works great and is much faster to test. I've never had a problem in 3 years and salinity is always the same

UFfishingirl · Jun 9, 2009

I work in an animal hospital and we use refractometers for blood and urine. What I usually do is just take some water to my work and test it there lol.

mike007 · Apr 23, 2013

Refractermeter is my choice.

Downbeach · Apr 24, 2013

I think if you have a FO tank a hydrometer is OK, except if you have to go hypo for an Ich outbreak then I think a refractometer is a necessity. I used to have an old Tropic Marin hydrometer that I used to use with success, but you had to make sure there weren't any micro bubbles attached, and you had to temperature correct, I broke it during a move one day. I also have two IO swing arm type hydrometers, that I use at my mixing station for rough estimates. Both of the IO hydrometers are kept clean, but both give me different readings. So, if accuracy is important, there is no doubt in my mind that a proplerly calibrated refractometer, or pinpoint monitor is best.