Refractometer calibration Questions

[riz94107]

I just bought some 35ppt calibration fluid; based on what I've googled, this should be 1.0264 at 25C, is that right? When I calibrate my refractometer to that value, distilled water comes out at less than 1.000; is this normal?
The refractometer I have claims to be ATC, and my room temperature is probably around 22-23C right now...

 

[Dr. Reef]

I have a ATC refractometer from h2o DD and using 35 standard salinity solution it calibrates fine but when u check it against Rodi water it's not 0 it's off. I trust the salinity solution as it's brand new and I have another cheap refractometer and Milwaukee digital salinity meter and I cross checked the solution so I don't bother Rodi water test anymore.

 

[Potatohead]

Don't worry about RODI just calibrate to the fluid.

 

[jason2459]

I have a ATC refractometer from h2o DD and using 35 standard salinity solution it calibrates fine but when u check it against Rodi water it's not 0 it's off. I trust the salinity solution as it's brand new and I have another cheap refractometer and Milwaukee digital salinity meter and I cross checked the solution so I don't bother Rodi water test anymore.

The DD H2Ocean is a seawater refractometer and should line up to 0 with Rodi. I would be suspicious of the solution.

http://www.reefcentral.com/forums/showthread.php?t=2583418

 

[Dr. Reef]

The DD H2Ocean is a seawater refractometer and should line up to 0 with Rodi. I would be suspicious of the solution.

http://www.reefcentral.com/forums/showthread.php?t=2583418

That was my first thought as well. I also have another salinity standard both measure perfectly on cheap refractometer and Milwaukee digital at 35 or 1.026. Does the same on h2o refractometer as well but when I check ro di water Milwaukee and cheap refractometer reads 0 while h2o refractometer does not.

 

[jason2459]

The Milwaukee should read 0 as it is a seawater refractometer. What cheap refractometer do you have as many are brine and should not be "0" with rodi when calibrated with 35ppt solution. Seems odd.

 

[otrips]

My refractometer came with bad fluid. I couldn't even calibrate it up to the solution. Calibrated it with RODI, verified with LFS & threw out solution.
So that's my suggestion. Bring it up to your LFS and have them check it.

 

[Dr. Reef]

I bought it on ebay (unbranded) as a salinity refractometer.
H2o calibrated at 35 reads 5 on Rodi water
Solution ( salinity standard made by 2 little fish) is right as I checked it against my LFS as well.

 

[Dr. Reef]

What's odd is all 3 calibrated at 35 are constant with saltwater and when checking against Rodi water earlier 2 read 0 while h2o refractometer reads between 5 to 7

 

[jason2459]

That is weird. Calibration near the target end point is always best. That is as long as the reference solution is accurate. I much prefer now to make my own with a nice scale.

 

[homer1475]

My refractometer came with bad fluid. I couldn't even calibrate it up to the solution. Calibrated it with RODI, verified with LFS & threw out solution.
So that's my suggestion. Bring it up to your LFS and have them check it.

Yeah cause every LFS around the country is a reputable business, and can be trusted. :debi:

FWIW, by time you take it to your LFS, have them calibrate with god knows what or how old their calibration fluid is, bump it around in your car on the ride home, it's more then likely already lost calibration.

If you can't carry out something so simple as calibrating a refractometer, this hobby might not be for you.

 

[otrips]

What the? Sorry but I trust my lfs. If I didn't it wouldn't be my lfs. And If you can't trust yours to calibrate one then it shouldnt be yours. I assume my lfs's refractometers are accurate, their solutions and more importantly their own tanks as everything is always healthy. If mine matches up all that then I'd say it's safe to say the calibration fluid I had was bad. And yes I'm capable of calibrating mine that's why I knew something wasn't right. Forgive me for double checking that in fact the fluid that was off and not the new refractometer.

 

[A sea K]

If you can't carry out something so simple as calibrating a refractometer, this hobby might not be for you.

Tad harsh there dont you think Homer.