D-D’s seawater refractometer might be the only one scaled for seawater, not saltwater

By Jake Adams on Jul 12, 2010

As far as we can tell, D-D’s Seawater refractometer is perhaps the ever such device that is scaled and calibrated for use with seawater. “That’s crazy talk” you say as you peer upon your aquarium refractometer which was likely designed for use with saltwater or brine, a solution consisting solely of sodium chloride (NaCl). By comparison, although seawater contains a majority of sodium chloride, it also includes a significant portion of magnesium, calcium, carbonates and all of the major, minor and trace elements we have come to know and love and which impart on seawater a significantly different refractive index than a pure brine solution. The difference between saltwater and seawater may be small but in the neighborhood of where we measure aquarium salt levels, where a proper seawater refractometer measures 29 ppt (1.022 s.g.), the average saltwater refractometer is telling you your salt level is at 32 ppt (1.024 s.g.). So you may think that your salt mix is low in calcium and alkalinity but in fact, you just need to add more salt mix to get your water to a proper salinity, silly.

If you currently own a refractometer, you can go ahead and recalibrate it using a seawater reference solution of a known salinity but there’s something inherently unfair about having to “fix” an expensive testing device which should do the right job in the first place. What makes the D-D seawater refractometer different is that the scale is also designed for seawater usage so you can calibrate the refractometer with pure freshwater at 20C and the rest of the scale will fall right in line with expected seawater refraction values. We must admit it was quite a jar to go around to all of our tanks with our Sybon and the D-D refractometers to find out that all of our tanks were actually at much lower salinities than we thought, explaining away a whole mess of issues we’ve had in the past with running hypo in a fish or reef, or issues with calcium and alkalinity from certain salt mixes. There’s a whole lot more we could explicate about the re[purcussions of this, but for now we’ll just direct you to a nice article on salinity and it’s measurement by Stuart Bertram of D-D the aquarium solution. The D-D Seawater Refractometer costs about the same as other refractometers and it is available from dealers of D-D Aquarium Solution products.

http://www.lightning-maroon-clownfish.com Matt Pedersen

Very, very interesting…
http://www.lightning-maroon-clownfish.com Matt Pedersen

Very, very interesting…
Mike

Hmm.. I always thought the refractometer because it worked via an optical principle didn’t matter what fluid you used. Hence the reason for using a standard that’s not necessarily salt water but something close in terms of SG.
Mike

Hmm.. I always thought the refractometer because it worked via an optical principle didn’t matter what fluid you used. Hence the reason for using a standard that’s not necessarily salt water but something close in terms of SG.
Michael

Its been a long fought battle to educate reefers that refracts are not designed for NSW, this came to light for us when the uptake in salinity probes took off, our support inbox was full of “your expensive salinity probe is not accurate against my $20 ebay refractometer”

Once the user was pointed in the right direction of calibrating to NSW then this issue goes away.

Nice to see D&D have come up with a fantastic product to this age old myth. Hope others now follow
Michael

Its been a long fought battle to educate reefers that refracts are not designed for NSW, this came to light for us when the uptake in salinity probes took off, our support inbox was full of “your expensive salinity probe is not accurate against my $20 ebay refractometer”

Once the user was pointed in the right direction of calibrating to NSW then this issue goes away.

Nice to see D&D have come up with a fantastic product to this age old myth. Hope others now follow
Geoff

Where are these available online or am I jumping the gun a bit?
Geoff

Where are these available online or am I jumping the gun a bit?
http://reefbuilders.com Jake Adams

The refractometers arrived at Xenia Inc in Canada at least a couple of weeks ago. Take a look at this page for retailers who might already have the Seawater Refractometer.
http://www.xeniainc.com/page-distribution.php
http://reefbuilders.com Jake Adams

The refractometers arrived at Xenia Inc in Canada at least a couple of weeks ago. Take a look at this page for retailers who might already have the Seawater Refractometer.
http://www.xeniainc.com/page-distribution.php
Tony

Am I the only one that thinks this product, while interesting, is a total waste? Chasing numbers is bad. mkaaay….
Tony

Am I the only one that thinks this product, while interesting, is a total waste? Chasing numbers is bad. mkaaay….
http://ballz.biz balistes

Yeah tony you’re the only one. Salinity is the alpha number which helps reefers makes sense of all the other numbers of reef aquarium chemistry. The difference between the saltwater and seawater salinities may be only a couple points but for example, if you’re runing hyposaline in a reef, the discrepancy could mean the difference between shrimp that are fine, and shrimp that are stressing or dying.
http://ballz.biz balistes

Yeah tony you’re the only one. Salinity is the alpha number which helps reefers makes sense of all the other numbers of reef aquarium chemistry. The difference between the saltwater and seawater salinities may be only a couple points but for example, if you’re runing hyposaline in a reef, the discrepancy could mean the difference between shrimp that are fine, and shrimp that are stressing or dying.
Jamie

Great to see this getting good press, I was using an old brine one and getting low magnesium issues with my water change water, until I bought one of these and calibrated it with a FM ref solution.
Jamie

Great to see this getting good press, I was using an old brine one and getting low magnesium issues with my water change water, until I bought one of these and calibrated it with a FM ref solution.
reef

The refractometer is not going to be any good for low salinity treatment as it does not go low enough.
reef

The refractometer is not going to be any good for low salinity treatment as it does not go low enough.
http://www.greateriowareefsociety.org Joe

I have had mine for a couple of months now and I love this refractometer. It is by far the best one I have ever owned!
http://www.greateriowareefsociety.org Joe

I have had mine for a couple of months now and I love this refractometer. It is by far the best one I have ever owned!
pickle

So, like you say in your post, it seems to me that this is more about using NSW calibration fluid than the actual refractometer, correct? Seems like the only difference is that refractometer has a narrower measurement range. I don’t mean to be dissing this product, but that really seems to be what this is about.

Either way, this illustrates the reason why I’ve always found my tank looks better when I keep the SG closer to 1.030 using my cheapo refractometer. Turns out it wasn’t really “elevated” afterall. Interesting.
pickle

So, like you say in your post, it seems to me that this is more about using NSW calibration fluid than the actual refractometer, correct? Seems like the only difference is that refractometer has a narrower measurement range. I don’t mean to be dissing this product, but that really seems to be what this is about.

Either way, this illustrates the reason why I’ve always found my tank looks better when I keep the SG closer to 1.030 using my cheapo refractometer. Turns out it wasn’t really “elevated” afterall. Interesting.
http://foxstats.com Mackenzie Honsinger

hi, I attempted to email you with respect to this post but aren’t able to reach you. Please message me when get a moment. Thanks.
http://foxstats.com Mackenzie Honsinger

hi, I attempted to email you with respect to this post but aren’t able to reach you. Please message me when get a moment. Thanks.
http://www.facebook.com/Jay.A.Glass Jason Glass

I have used this for 3-4 months now and I like it better then my other 2 refractometers (one from ebay and one from Marine Warehouse).

Related posts: