Hydrometer/Refractometer

[newfishhobbyist]

Hi all. I'm reading that a refractometer is the way to go. Any suggestions on brands or are they all the same?

Thanks!

 

[HN1]

I'm not sure that the brands really matter much as long as they are calibrated properly. I'm happy with the one we got from Drs for around $40. WAY better than a hydrometer IMO.

 

[roka64]

Make sure you get an ATC one. I got the same one off the Dr's website (probably as HN1's).

 

[melosu58]

I'm not sure that the brands really matter much as long as they are calibrated properly. I'm happy with the one we got from Drs for around $40. WAY better than a hydrometer IMO.

Same here

 

[errdivideby0]

I ordered one off of ebay for about 30 bucks and it seems to be working fine. I calibrate it before I use it every time to 1.0 using purified water and I haven't had any problems.

 

[newfishhobbyist]

Thanks!

 

[Kurt_Nelson]

Better to calibrate it using 53.0 mS conductivity calibration solution that Pinpoint makes for the electronic salinity meters. It should read about 1.026+. That way you're calibrating in the range that you're measuring, and not just at 1.0

 

[Ziggy953]

I got mine off marinedepot.com check there as well they tend to run sales on their brand.

As for calibrating I've always calibrated to 0 using RO/DI water. If it reads 0 then it will read 1.026 or what ever your SG is.

 

[Kurt_Nelson]

If it reads 0 then it will read 1.026 or what ever your SG is.

Not necessarily... but if yours does, that's cool! Linearity of the things can vary from brand to brand, batch to batch. I've been pretty happy with my Sybon from Premium Aquatics.

 

[severum mama]

Not necessarily... but if yours does, that's cool! Linearity of the things can vary from brand to brand, batch to batch. I've been pretty happy with my Sybon from Premium Aquatics.

Happy to hear it... we also have a Sybon. You're talking like 20 miles over my head so I'm satisfied that you're satisfied.

 

[Kurt_Nelson]

Happy to hear it... we also have a Sybon. You're talking like 20 miles over my head so I'm satisfied that you're satisfied.

Not sure what part is confusing, but let's see if I can say this different...

Calibrating with pure RO/DI water will make sure your refractometer reads 1.000 when the water is at 1.000. But refractometers - even though they're far more accurate than most hydrometers - can still be off. In a perfect world, if you calibrated your refractometer to any solution with a known salinity, it would read perfect for all other salinities.

But the world ain't perfect, and there's nothing that says a refractometer has to read linear - in other words, as you move away from that calibration point, the reading may be higher or lower than reality.

Since the water we're testing isn't at 1.000 specific gravity, it's better to calibrate with a solution that is closer to what we keep our tanks at. That way, any linearity error in the refractometer is minimized. If you calibrate your unit with a 1.026 solution (the 53.0 mS solution I mentioned - can be bought at most places that sell the Pinpoint brand conductivity/salinity meters), and your water in the tank is 1.026, then you're pretty much guaranteed no error.

Like I said, I'm happy with the Sybon... but even with it, when I calibrate at 1.026, and then check 1.000 with RO/DI water, I'm about .001 high.