refractometer vs hydrometer proven results

[MGDMIRAGE]

Most calibration solutions aren't just purified water but water at a SG of 1.026. Most refractometers that i have seen recommend calibrating with DI water. I did mine that way too and it was way off compared to when I used calibration 53ms solution. My hydrometer has been tested against a refractometer and it has always been pretty dead on btw, they aren't all crap

 

[dawgwe1]

I just got a refractometer in the mail. It said to calibrate with RO water so I did. I found that my tank with the hydrometer is reading 1.024 and with the refractometer it is reading 1.020!!!! Going to get some calibration solution before I make any changes. I find it hard to believe my coral and such would be growing at a 1.020 salinity level. May double check with a fellow reefers meter as well.....

 

[godzen]

I just got a refractometer in the mail. It said to calibrate with RO water so I did. I found that my tank with the hydrometer is reading 1.024 and with the refractometer it is reading 1.020!!!! Going to get some calibration solution before I make any changes. I find it hard to believe my coral and such would be growing at a 1.020 salinity level. May double check with a fellow reefers meter as well.....

yeah, I think once i get my refractometer and compare it to my float type to gauze the difference, I see myself using the float type 99% of the time. I'm new to the hobby but I think there are simply too many people wasting dollars chasing the smallest of things

 

[dawgwe1]

I am going to get a floating gauge as well. Use as a back up and also to make sure from time to time the meter is calibrated. I had one years ago, but as you know, the top stem is what seems to break off at some point.........

 

[rayjay]

Is this refractometer a salt water version or a seawater version?
Did you read the link to Randy's article in post 10 above?
If you buy a floating hydrometer, buy a columnar cylinder to put the water in and then put the floating hyrometer in. Don't use it in the tank.
Check to see what the calibration temperature of the hydrometer is as most quality ones need compensation charts.

 

[Boomer]

I did not read it all but you guys seem to missing some points.

1. A floating hydrometer has to have a cal input temp and a read temp

Hydrometer to Salinity Calculator


Example: Cal to 77 F- 77F, Tank temp 82 F, Hydrometer reading 1.0264 real salinity 36.2 ppt and not 35 ppt which it would give, if the Tank temp is 77 F or the same as the Cal temp.

2. Refracts sold that give RO/DI water foir cal are of 95 % of the time, as they are NOT Seawater Refracts but Table salt, aka, NaCl refracts. Light is NOT refracted the same in seawater as it is in NaCl, which these refract you guys are posting on are. There are only 2 true seawater refracts in this hobby, the Vee-Gee and the Vital Sin, which are both the same with a different name on them. We have tested these many times. The PinPoint 53 mS cal solution is really a mock seawater solution, which can be used to cal, refracts, conductivity meters an hydrometers. Any refract, even a true seawater refract ( even though they can be cal in RO/DI water) should be cal in a std solution, that is real seawater or a mock seawater, which are the same as far as measurement goes. Reason, to just be more sure of your measurement.

will get ur calibration solution and post tests of it. i hypothisise it will be the same.its just sealed di in a packet to ensure no contamination

No it is not DI water in a package it is seawater in a bottle. If you check its conductivity it will me 53 mS and if you check its RI (Refractive Index) at 35 ppt it will be 1.33940 @ 20 C

You guys need to be reading this :

Refractometers and Salinity Measurement
Refractometers and Salinity Measurement by Randy Holmes-Farley - Reefkeeping.com


Temperature Corrections for Hydrometers
Temperature Corrections for Hydrometers by Randy Holmes-Farley - Reefkeeping.com


Specific Gravity Measurement
Chemistry and the Aquarium: Specific Gravity: Oh How Complicated! — Advanced Aquarist | Aquarist Magazine and Blog

 

[rayjay]

Hey Boomer, I think you've been up too long without sleep. Hygrometer??:biggrin1:
As for point one, I posted Randy's link to the refrac. page but I don't think everyone read it thoroughly from the postings that came after.
I also mentioned that a decent quality hydrometer would need compensation charts. However, there are hobby floating hydrometers out there that are calibrated in the 77 to 80° range so any adjustment would be very minor.
Unfortunately though, many use these by floating the hydrometer in the tanks so they get improper readings.

 

[senji]

ok to update u guys i did pick up some calibration soultion and ran the calibration soulution though the centrifige and found it to be off by .0005 but who care right. off by so little. but did mix up some of the salt i use coral pro salt to .026. took a while to get it to molar perfect. like 3 days till the centrifuge read perfect .026 and by the way that salt almost is perfect to the numbers on the bucket advertised. which is ca 450 tested 453, mg 1340 tested 1334, alk 12.2 tested 12.5. this was done with a lab cetrifuge.but to end this long story i found my refractometer to be acurate after calibrating with true distilled water at 0ppm. checked with the water it took so long to make molar perfect. .026 or 36ppt

 

[Boomer]

Did you forget to put your glasses on again or were you up to late "hygrometer' ;-)


I was with Sanjay for the last few days and up till 3:00 AM each night. So, I would have an excuse



There are no hydrometers above 77F ;-) There are, 15C(59F) , 60F, 20C(68F). 75F and 77F.


Yah, I saw some of that posted. But one link just took you to the Chem articles page.

 

[Boomer]

calibration soulution though the centrifige

What do you mean you checked it with a lab centrifuge. The only accepted procedure is the K-15 Method for Salinity.

K[SUB]15 = [/SUB]Conductivity of the Seawater Sample/ Conductivity of the Std KCl Solution.

Where Std KCl = 32.4356g / kg[SUP]-1[/SUP], @15 C and 1 Atm

S = 0.0080 - 0.1692 K[SUP]1/2[/SUP] + 25.3853 K + 14.0941 K[SUP][SUB]3/2[/SUB][/SUP] - 7.0261 K[SUP]2 [/SUP]+ 2.7081 K[SUP]5/2[/SUP]



ike 3 days till the centrifuge read perfect .026- 36 ppt

What do you mean molar perfect, 1.026 = 35 ppt not 36 ppt.

That is Sg, how, at what temperature.

the way that salt almost is perfect to the numbers on the bucket advertised. which is ca 450 tested 453, mg 1340 tested 1334, alk 12.2 tested 12.5.

The only accepted method for Ca++, Mg++ is ICP and for Alk it is Titration Std Seawater Procedure.

my refractometer to be acurate after calibrating with true distilled water at 0ppm

It can't you are defying laws of physics. Even if it did it means nothing as we have found some of these cheap refract off as much a 0 - 5 ppt depending on the cheap optics of the glass and poor quality control. A expensive lab grade NIST Certified will be of - 1.5 ppt to low. Did you even read the articles posted ?

calibration solution

Who's ? Not ALL 53 mS solutions are the same. It must be Pinpoint 53 mS only. If you are going to be checking that solution use only a Conductivity meter.

You need a copy of this or equal to it

Analysis of Seawater : A Guide for the Analytical and Environmental Chemist by T. R. Crompton (May 1, 2006)

 

[senji]

its a machine at the colledge that separates all elements and measures them electronically i think it cost round 350k for the centrifuge. i have full acces to the bio chem lab

 

[senji]

and molar weight is tru molecular weight.

http://web.viu.ca/krogh/chem311/units of concentration.pdf

thats all this machine measures is concentration

 

[senji]

the professer helping me has a masters in Quantum Mechanics so im pretty shure we are dooing it right

 

[Boomer]

I know what molar mass is and don't need lessons on it. So, let me give you some lesson on molar mass and Salinity.

Seawater is 35 ppt = 35 parts per thousand. That means that if you took 1 kg of std seawater and evaporated 100 % of the water you will have 35 grams of dry mass. Or to look at it the other way. If you had a salt mix that was made up of 100 % unhydrated salts and weighed out 35 grams and added it to 965 ml of RO/DI water, which now equals 1 kg. That 35 grams gives 3.5 % solution or 35 ppt.

965 + 35 = 1,000 g or 1 kg. What is 35 grams in 1,000 grams ?

35 / 1,000 = 3.5 % and 3.5 x 10,000 = 35,000 ppm or 35 ppt.

Do you really know what molar mass is ? 1 mole of calcium weights 40.078 grams and that 1 mole or 40.078 grams has 6.02 x 10[SUP]23[/SUP] "atoms " of calcium. 1 mole is 6.02 x 10[SUP]23 [/SUP]"things" be it photons, Ca++, sand grains, molecules or even rabbits. 435 ppm Ca++ is not 1 mole but 10.85 mM, as in milimoles. I can have 10.85 mM of Mg++ if I want. So, how is that machine going to determine it is Ca++ or Mg++ ? It can't

So, this cal solution we are talking about or the one you seem to be talking about can not have 0 grams of salts can it ? Second point. No centrifuge can separate out multiple different ions. Meaning, just Calcium. How can it by any laws of physics or chemsitry tell that x sample has 435 ppm calcium, when that same sample has 34, 565 ppm of other ions ?

Please point me to a link of said machine/centrifuge that can tell you how much of x ion there is in a solution. Yes, you can use a centrifuge for the separation of salts in a solution but it can not tell you the concentration of the individual ions. You must go to the next step such as ICP

You are also not answering the question What solution are you testing ?

The guy that wrote those article I posted has a PhD from Harvard University. Are you telling me he does not know what he is talking about . He runs a analytical research lab and has more than 50 patents on chemicals. Would you like me to bring Randy here ? Why don't you bring your college professor here too :biggrin:




PS

Thank You Rayjay for pointing out some bad spelling errors on my part.

 

[1guydude]

bring em to my house! I want my mind blown! :`/

 

[Krish]

bring em to my house! I want my mind blown! :`/

Inb4 I read about 1guydude's mind being blown. :shock:


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