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About refractometers. Ppt or sg? Is one more accurate or better to use? I've been using sg but after research, seems ppt is better?
Got red sea and vee gee and both per manufacturer instructions say to use distilled or rodi water. I've always been using rodi to calibrate. If that "magic" calibration solution was really necessarily, the manufacturers would use it themselves.That makes no difference and cannot impact accuracy, except if it is a brine refractometer (most are if they do not say true seawater refractometer)) and you calibrate with RO/DI, in which case both are inherently inaccurate.
If you calibrate with a 35 ppt/sg = 1.0264 standard, you can use either scale just fine.
PPT seems to be the industry standard use. I prefer SG but they calculate to same safe rangeAbout refractometers. Ppt or sg? Is one more accurate or better to use? I've been using sg but after research, seems ppt is better?
Got red sea and vee gee and both per manufacturer instructions say to use distilled or rodi water. I've always been using rodi to calibrate. If that "magic" calibration solution was really necessarily, the manufacturers would use it themselves.
OK, let us know what they say.
I've seen lots of posts using that method with bad results. Instantly fixed by calibrating with actual calibration fluid.Got red sea and vee gee and both per manufacturer instructions say to use distilled or rodi water. I've always been using rodi to calibrate. If that "magic" calibration solution was really necessarily, the manufacturers would use it themselves.
So here is the response about the STX-3. I asked “is this refractometer a true seawater refractometer or a brine refractometer?”
They said,
“Our refractometer uses the scale for seawater, not just a brine.”
Seems vague to me. If I make your standard using your recipe and use it with the VeeGee after calibrating with distilled and it reads as it should, does that mean it’s seawater?
Idk, I've heard the same bad claims bout calibration fluid. Same bad reviews on the calibration fluid and how it's not accurate, either due to expiration, brand, temp. I figure I've been using rodi past 6 months no problems, I'll keep it the same.I've seen lots of posts using that method with bad results. Instantly fixed by calibrating with actual calibration fluid.
After calibrating both vee gee and red sea per manufacturer instructions, many times, both refractometers give the same reading. My 3rd ato non brand one gives 2-3 sg .00 points higher reading. I stopped using itIt's not nearly so simple as you assume, and in this case, you assumed wrong. This is the sort of reason why there is a reef chemistry forum rather than a page of links to manufacturer claims, which are frequently misleading or just plain wrong.
Certainly manufacturers recommend pure fresh water for calibration, and that is always correct for the chemicals the refractometer is made for.
Unfortunately, very few refractometers are made for seawater and so that is the wrong advice when using those types for seawater rather than their intended use.
If the Vee Gee you have is the STX3, it is likely not a true seawater refractometer. You can tell that by the vague claim of what it can be used for:
Salinity Refractometer with ATC
Buy Salinity Refractometers from VEE GEE Scientific today! Order Online for Free Shipping & Fast Delivery.www.veegee.com
"Handheld Salinity Refractometers are exceptionally simple to operate and provide quick, accurate measurements for the concentration of nearly any aqueous solution."
The Red Sea is a true seawater refractometer. They specifically note the problem with non seawater refractometers:
Seawater Refractometer - Red Sea Salinity test for marine aquariums
Red Sea’s Seawater Refractometer offers exceptional accuracy, for measuring the absolute salinity of seawater Specifically designed for saltwater aquariumswww.redseafish.com
"Most refractometers used within the aquarium hobby are not specifically designed for reef aquariums and use an algorithm for the measurement of brine (NaCl – rather than seawater) and at a temperature of 15oC/59 0F rather than 25oC/77 0F. Thus, a measurement deviation of up to 1.5ppt is possible, which can have a significant adverse effect on coral growth and coloration."
Does calibration fluid go bad? If so, how long does it last?
Thank you
Troy