Use calibration fluid they said!

[Derrick0580]

So after seeing soo many reefers saying to use calibration fluid to set my refractometers I grabbed a bottle while I was at a lfs. Got home and made up a batch of water in a 5 gallon bucket. I don’t weigh anything, just drop pump and heater in and add a little salt, wait and check, add more salt, wait and check till it’s where I need it. Since I had calibrated two different refractometers with the pinpoint fluid I figured I had better double check the salinity with my tropic marin hygrometer and so glad I did. My hygrometer was reading 1.035 where as both of my refractometers read 1.026. My refractometers are one red sea branded and one no name petco generic. I then recalibrated both of them using plain rodi water and wouldn’t you know….they both match the hygrometer. Never again! They can stick calibration fluid where the sun doesn’t shine!

 

[KQuillan]

I agree! Using the fluid made mine 6 points off.

 

[flashsmith]

I only use the tropic Marin one. I killed a bunch of corals using and trusting a Hanna salinity meter.

 

[Randy Holmes-Farley Verified Community Expert]

So after seeing soo many reefers saying to use calibration fluid to set my refractometers I grabbed a bottle while I was at a lfs. Got home and made up a batch of water in a 5 gallon bucket. I don’t weigh anything, just drop pump and heater in and add a little salt, wait and check, add more salt, wait and check till it’s where I need it. Since I had calibrated two different refractometers with the pinpoint fluid I figured I had better double check the salinity with my tropic marin hygrometer and so glad I did. My hygrometer was reading 1.035 where as both of my refractometers read 1.026. My refractometers are one red sea branded and one no name petco generic. I then recalibrated both of them using plain rodi water and wouldn’t you know….they both match the hygrometer. Never again! They can stick calibration fluid where the sun doesn’t shine!

Maybe you should make your own and not trust that the ones at an lfs have not been adulterated.

RO/DI is inaccurate for many refractometers. it is not a guess. If they are correctly made, they must be inaccurate when calibrated with RO/DI.

 

[Randy Holmes-Farley Verified Community Expert]

I agree! Using the fluid made mine 6 points off.

Then you used an incorrect fluid.

 

[rtparty]

How old was the fluid? How long was it sitting on the shelf?

If you weigh your salt, you don't even have to check salinity and worry about all that.

 

[KQuillan]

Then you used an incorrect fluid.

Fritz Aquatics 35ppt (1.026sg) Refractometer Calibration Solution​

 

[KQuillan]

Fritz Aquatics 35ppt (1.026sg) Refractometer Calibration Solution​

Sorry for the bold print (copied), I also noticed this didn't get very good review. Any recommendations?

 

[KStatefan]

Sorry for the bold print (copied), I also noticed this didn't get very good review. Any recommendations?

Make you own

 

[Just John]

I ended up with 3 calibration fluids and using the expensive refractometer from my lab, they all gave different results.
I concluded that AccuraSea was most accurate, Aquatic Experts brand and Brightwell Aquatics brand were not. In a few places I have seen that you should not use rodi to calibrate. I don't remember why.
On the subject of refractometers, I was curious if my $35 refractometer was accurate and my cheap one matched that expensive one from the lab and so did my friends cheap refractometer, so I guess the bargain ones work fine.

 

[Derrick0580]

Randy, can you link me a site on how to make my own fluid? As far as the age of the fluid, that I do not know. I sent the lfs a fb message after I discovered the issue and asked them the exact same question. There is no date on the bottle and the bottles were just in sealed clear bags and no box.

 

[ying yang]

http://reefkeeping.com/issues/2004-06/rhf/index.htm

Here you go
Good luck

 

[KQuillan]

I ended up with 3 calibration fluids and using the expensive refractometer from my lab, they all gave different results.
I concluded that AccuraSea was most accurate, Aquatic Experts brand and Brightwell Aquatics brand were not. In a few places I have seen that you should not use rodi to calibrate. I don't remember why.
On the subject of refractometers, I was curious if my $35 refractometer was accurate and my cheap one matched that expensive one from the lab and so did my friends cheap refractometer, so I guess the bargain ones work fine.

Thank you.

 

[Randy Holmes-Farley Verified Community Expert]

Fritz Aquatics 35ppt (1.026sg) Refractometer Calibration Solution​

If it failed, it was the wrong fluid or you used it incorrectly.

I do not know if Fritz knows how to make them, or if it may have been adulterated in the store (a well known problem at stores that allow returns and resell things),

 

[capted]

Been down that road before. Tried every calibration fluid I could find with different results on all of them. Then I made my own using Randy's formula(thank you Randy). The only calibration fluid that matched Randy's was Accurasea like someone mentioned. I have gone through numerous bottles and they all seem to match.

 

[Derrick0580]

You think the accurasea would be safe to order from amazon?

 

[Derrick0580]

And while we are on calibration fluids, what brand is the best for calibrating ph probes? I calibrated a new pinpoint probe and it was reading 7.9-8.4, then bought a 20 pack of 7 & 10 fluids off amazon to recalibrate and it’s reading 7.2-7.5. Is there a way to rule out a bad probe or bad fluid? I have a brand new probe on hand but if it’s bad fluid it would just be a waste of time to switch out the probes.

 

[capted]

You think the accurasea would be safe to order from amazon?

Yes. I ordered some from Amazon.

 

[capted]

And while we are on calibration fluids, what brand is the best for calibrating ph probes? I calibrated a new pinpoint probe and it was reading 7.9-8.4, then bought a 20 pack of 7 & 10 fluids off amazon to recalibrate and it’s reading 7.2-7.5. Is there a way to rule out a bad probe or bad fluid? I have a brand new probe on hand but if it’s bad fluid it would just be a waste of time to switch out the probes.

Take your time doing the calibration. Let the probe sit in the fluid for 10 minutes and calibrate 7.0 then do the 10.0 the same way. Repeat the same process about 5 times. Also check the temp of the fluid and adjust the calibration as per the chart on the back of the package.

 

[mindme]

So after seeing soo many reefers saying to use calibration fluid to set my refractometers I grabbed a bottle while I was at a lfs. Got home and made up a batch of water in a 5 gallon bucket. I don’t weigh anything, just drop pump and heater in and add a little salt, wait and check, add more salt, wait and check till it’s where I need it. Since I had calibrated two different refractometers with the pinpoint fluid I figured I had better double check the salinity with my tropic marin hygrometer and so glad I did. My hygrometer was reading 1.035 where as both of my refractometers read 1.026. My refractometers are one red sea branded and one no name petco generic. I then recalibrated both of them using plain rodi water and wouldn’t you know….they both match the hygrometer. Never again! They can stick calibration fluid where the sun doesn’t shine!

I use brightwell calibration fluid, and my ICP tests all come back with near perfect salinity.