Refractometer Calibration

[dbartco]

For the meeting on the 23rd:

 

YBNormal has volunteered to set up a refractometer calibration table with commercial calibration solution. BRING YOUR REFRACTOMETERS if you would like to verify your salinity readings!

[jason the filter freak]

For the meeting on the 23rd:

 

YBNormal has volunteered to set up a refractometer calibration table with commercial calibration solution. BRING YOUR REFRACTOMETERS if you would like to verify your salinity readings!

 

I.e. RODI? or am i missing something, cept for the meeting I won't be missing that

[mogurnda]

I.e. RODI? or am i missing something, cept for the meeting I won't be missing that

 

Because the response curves of our cheap refractometers aren't linear, RO/DI is a lousy calibration fluid. A commercial calibration fluid in the range of interest (as above) or a homemade equivalent is much better.

[dbartco]

A 35ppt calibration solution is used. If it ain't 35ppt on your little pocket rocket, you might want to know.

[bigJPDC]

I am bringing my Deep6 swingarm for this excercise!

[dbartco]

I should point out this should be for refractometers only (you only need a few drops). The calibration solution comes only in a few ounces per bottle. You could bring, and maybe at the end use if there is enough left. There are a lot of home diy solution calibrations you can search for as well, which make a 2 liter sized. But the commercial calibration comes in a 3-4 oz container.

 

Sorry JP. You should try the refractometer. You will find them as easy as the swing arm, and much more accurate.

[bigJPDC]

ahh - OK doug, I was thinking about checking it with tank water from one of the frag tanks vs. the calibrated refractometers for giggles. No biggie.

[lanman]

I am bringing my Deep6 swingarm for this excercise!

Woohoo! I can bring mine, and you can calibrate yours against it! When I got my refractometer, I calibrated my Deep-6 against it. And found out that all my little reef inhabitants were living in hypersalinity. Mine reads .005 LOW. i.e. 1.025 on the deep-6 actually = 1.030. And my salinity had crept up to about 1.027/1.028 on the deep-6. Almost dangerous - definitely not 'spec'.

 

bob

[dbartco]

Or, DUH! Those of you with swing arms come on down with a water sample of their own tank, and find a calibrated refractometer buddy to compare it with. Sometimes me not so bright...

[YBeNormal]

I stopped by BRK today and they only had one bottle of Pinpoint 35ppt calibration fluid left. Johnny was kind enough to donate it to WAMAS though and one bottle should be enough to calibrate all of our refractometers.

 

For those of you who don't understand why we are setting this up, the issue is that many of our cheap-o refractometers are not as accurate as we thought they were. Check out this article and this thread on RC for more information.

Thanks to Johnny / BRK for once again donating items to support the WAMAS community!

[lanman]

I stopped by BRK today and they only had one bottle of Pinpoint 35ppt calibration fluid left. Johnny was kind enough to donate it to WAMAS though and one bottle should be enough to calibrate all of our refractometers.

 

For those of you who don't understand why we are setting this up, the issue is that many of our cheap-o refractometers are not as accurate as we thought they were. Check out this article and this thread on RC for more information.

Thanks to Johnny / BRK for once again donating items to support the WAMAS community!

Okay - NOW I think it's time for a tank visit I'll call. And bring my refractometer (or as I like to call it - my mass spectrometer)

 

bob

[YBeNormal]

Sounds good. Give me a call and let me know when you will be in town.

 

I checked the blue RHS-10ATC refractometer I purchased from drsfostersmith.com for ~$40 a couple of years ago and I guess I lucked out. It was on the mark with both RO/DI and 35ppt solution, no recalibration needed. From what I've read, it's the cheap blue ones that are often inaccurate.

[yauger]

nice count me in, I have always been told to use ro/di to calibrate the refractometer but this seems more acurate

[toastiireefs]

Sounds good. Give me a call and let me know when you will be in town.

 

I checked the blue RHS-10ATC refractometer I purchased from drsfostersmith.com for ~$40 a couple of years ago and I guess I lucked out. It was on the mark with both RO/DI and 35ppt solution, no recalibration needed. From what I've read, it's the cheap blue ones that are often inaccurate.

 

i have that one too...

i like it but i dont know how accurate it truely is...

 

i calibrated it to fw.. so am i good?

i wont be at the meeting on the 23rd i dont think idk if i'll be home even though the meeting is like 3 miles away from me at one of my schools many rival schools..

[YBeNormal]

i calibrated it to fw.. so am i good?

 

Maybe. Maybe not. Checking against a 35ppt reference solution is the best way to find out.

[toastiireefs]

and i can make this..

 

i also checcked with mixed 1.019 solution.. and it checked out (i dont know how many ppts that is)

[YBeNormal]

i also checcked with mixed 1.019 solution..

 

I'm not sure I understand what you mean. How do you know it is 1.019?

[toastiireefs]

from the salt mix it says what a certain concentration mixes as...

idk i could not be understanding what you guys are talking about

[YBeNormal]

Ah, I see. A certain measurement of salt in a certain quantity of water and it's supposed to end up resulting in a certain salinity. That is a good way to judge roughly how much salt to add to your water but you still need to use a hydrometer, refractometer or probe to measure the actual SG.

 

Marine mix can absorb moisture over time and clump or compress such that a quantity of the powder measured using a cup or even a weight scale may actually be more or less than the recommended amount. You are then relying on the accuracy of your refractometer (or other device) to confirm that the SG is where you want it to be.

 

Hopefully that makes sense. If not, keep asking questions!

[jnguyen4007]

When do we take the reading, 24 hours after mixing the salt water? If the salinity is not on que, do we add salt or water depending on the reading and take another reading afterward, or do we need to wait for another period of time to take the reading?

 

James

[toastiireefs]

Ah, I see. A certain measurement of salt in a certain quantity of water and it's supposed to end up resulting in a certain salinity. That is a good way to judge roughly how much salt to add to your water but you still need to use a hydrometer, refractometer or probe to measure the actual SG.

 

Marine mix can absorb moisture over time and clump or compress such that a quantity of the powder measured using a cup or even a weight scale may actually be more or less than the recommended amount. You are then relying on the accuracy of your refractometer (or other device) to confirm that the SG is where you want it to be.

 

Hopefully that makes sense. If not, keep asking questions!

 

yes i think that makes sense--

and yes ive oticed the clumping on my last bag of salt- but now i have an air tight bucket! so it all stays powdery!

 

so is what your saying good or bad

i use my fosters refractometer!!

[YBeNormal]

You can take the reading as soon as the marine mix is fully dissolved and dispersed in the water. I usually take a rough reading within a few minutes after adding marine mix or RO/DI then wait a few hours and check again. I wait at least 24 hours (and check SG again) after making a new batch before adding it to my tank but I may only wait a couple of hours after making minor adjustments to the SG of the replacement water.

[lanman]

Sounds good. Give me a call and let me know when you will be in town.

 

I checked the blue RHS-10ATC refractometer I purchased from drsfostersmith.com for ~$40 a couple of years ago and I guess I lucked out. It was on the mark with both RO/DI and 35ppt solution, no recalibration needed. From what I've read, it's the cheap blue ones that are often inaccurate.

Mine's blue - but it cost me $100. Of course - that was at a store that is not well known for its great prices. One of these days real soon I'll have a quiet evening and will give you a call. You're only about 10 mins away.

 

bob

[YBeNormal]

Bump...

 

Reminder: Don't forget to bring your refractometers on Saturday for free calibration check and adjustment.

This service is sponsored by WAMAS (table and location) and BRK (calibration fluid)!