"Also, would you agree that Coralife statement of +/-0.001 SG accuracy of their
DEEP SIX is not true if you say +/- 1ppt refractometer is "much more accurate"?"

If you went out and bought 10 of each the refracts would be 9 out of 10, right on for a 35
ppt NaCl solution. The Deep-Six, 9 out of 10 would be all over the place.

" We knew something was wrong with them and we wanted
something reefers could make easily for a DIY calibration solution. The first ones we had
were to low."

AND

"I will wait then... thanks. But now I remember I have a postal scale with 1g accuracy...
It should give me accurate enough result for the calibration.""

You don't have to wait it has already been done go back and re-read the other post, that
is the new one. I gave a link to it.

" Adding on top
of it +/- 1ppt manufacturer stated measurement error margin we could be off by
more than 2.5 ppt if we do not correct NaCl offset..."


They are rarely off that much. What that means is that they guaranteed no more than that.
Even a $250 NIST certified hydrometer is + / - .001. Even the $ 600 fiberoptic
refract , for SEAWATER is only +/- 1 ppt. If you want to get accurate you need a
conductivity meter starting a + $400 to get it to 0.1 ppt.

If you use our stds. you will know exactly where you are at, with the refract and
Deep-Six


Boomer

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If You See Me Running You Better Catch-Up
"Pszemol" wrote in message ...
: "Boomer" wrote in message
...
: There is less error involved with a refract. I have yet seen a Deep-Six that is even
close
: to what it should read. Swing arms units also have a habit of collecting salt deposits
on
: the swing arms and pin, which can cause very low readings. Thus, they need to be
soaked in
: vinegar every month to remove such deposits. Floating hydrometers have the issue of
temp
: compensation, where most in this hobby seem to get lost. Refracts are much more
accurate
: out of the box. However, they are also in error but we can compensate for that.
:
: Looking at the scale of mine refractometer with divisions for 34 and 35 ppt so close
: to each other and comparing wide scale of swing arm with a centimeter between 34 and 36
: is it hard to believe refractometers are "much more accurate"... But I will take your
word.
:
: Also, would you agree that Coralife statement of +/-0.001 SG accuracy of their
: DEEP SIX is not true if you say +/- 1ppt refractometer is "much more accurate"?
:
: For the
: last couple of months Randy and I have been colleting data so he could redo the old
DIY
: calibration solutions from months ago. We knew something was wrong with them and we
wanted
: something reefers could make easily for a DIY calibration solution. The first ones we
had
: were to low.
:
: I will wait then... thanks. But now I remember I have a postal scale with 1g acuracy...
: It should give me acurate enough result for the calibration.
:
: In short your refract reads 1.5 ppt to low. So if you want a salinity of 35
: ppt (3..5 %), on your refract, it needs to read 36.5, which equals 35 ppt NSW.
Refracts
: from the factory are not calibrated to seawater but NaCl, which does not have the same
RI
: ( Refractive Index) as NSW. You can read all about it here. It just came out the other
day
: :-)
:
: Thank you.
: So it looks like people adjusting their tanks to a refractometer reading 35 ppt
: are really using sea water with less than 34 ppt of salt in it... Adding on top
: of it +/- 1ppt manufacturer stated measurement error margin we could be off by
: more than 2.5 ppt if we do not correct NaCl offset... Sounds very pessimistic :-)