Refractometer or not?

[msnajkowski]

I just got me a Refractometer this past weekend. My Hydrometer was saying 1.024. When checked with the Refractometer it was 1.030!!! Bite the bullet and stay away from Hydrometers.

 

[cameron]

Dakota wrote: There is a bit of controversy about calibrating refractometers.

I have a cheapo RHS-10ATC (blue handle). They are actually made for testing NaCl brines (like for pickles) and not seawater. There is a difference in the ionic makeup between the two that will alter the refractative index.
Refracts designed for testing seawater are actually very expensive, several hundred dollars.

Randy Holmes-Farley on RC did a lot of work on this and discovered that it is best to calibrate the cheaper refracts with Pinpoint's Salinity Meter Calibration fluid. Use it instead of RO/DI or distilled and calibrate to 1.0264.

The closer you calibrate the refract to where you will actually be measuring, the less it will be off. Calibrating to 0 in this case might cause a greater chance for inaccuracy.

I initially calibrated mine to 0 with RO/DI and used it for a few months. Was pretty proud of myself for switching from the swingarm that was a few points low. My tanks really didn't look very happy after a while. I read that article and ordered it from Premium Aquatics. After calibrating with it, I found that my tanks were at 1.031 rather than 1.026.

Some of these refracts aren't too far off, some are dead on, and I'm the lucky guy who got a dud. That calibration fluid was the best $4 I have spent on this hobby.

Calibrate with the Pinpoint solution to 1.0264, rinse and clean the plate really good, and then take a reading of RO/DI water to see how far you are off. If it still reads 0, then you can trust your refract for measuring hyposalinity in a hospital tank also. I can't with mine.

Great post and some rep points for you.

 

[broreefr]

I just picked up a refractometer as well, it turns out that my Hydrometer was pretty accurate, but I may well have just been lucky and got a good one. I do like the refractometer much better, it is easy to use, less messy, and I am sure now that I am getting correct readings

 

[flyingarmy]

Frewl wrote: I've just got a swing arm hydrometer and I was thinking about getting this refractometer from Aquabuys:
http://www.aquabuys.com/miva/merchant.mvc?Screen=PROD&Product_Code=mi_refractometer_atc&Category_Code=r2&Product_Count=1">http://www.aquabuys.com/miva/merchant.mvc?Screen=PROD&Product_Code=mi_refractometer_atc&Category_Code=r2&Product_Count=1</a>


Is a refractometer worth the extra expense or should I just go buy a new swing arm once a year like the guy at the LFS said to?

Billy[/QUOTE]

Ebay is your friend!!!:up:

 

[kappaknight]

Why not just use the drink test?

In all seriousness, this may sound stupid but make sure you rinse (or fill and empty) the dropper a couple of times with RO water after measuring or with the salt water right before measuring to wash away any dried salt that may have accumulated since your last test.

 

[cameron]

I know this isn't the best way to do this, but my lazy butt sticks my fingers in the tank and drips some onto the glass. I don't use a pipette. I save the pipette for calibrating. If you are really anal, you can just buy a bunch of pipettes. Here is a box of 500 which will last a few years for $30

 

[xyzpdq0121]

I just got my e-bay special refracto in and am loving it... Worth every penny of the $25 I paid... Now to do like I did when I got my PH pen first in.... test everything in sight starting with my main tank, QT tank, and Hospital tank!