Refractometer Calibration Liquid Possibly Faulty

[stevo01]

Yea sure




Yes.

Yes what?

 

[bif24701]

Yes what?

The cover should lay flat on its own, but if you need to assist it that's fine.

A very good tip to remember anytime you are testing is to do the same procedure every time no matter what your testing for.

 

[stevo01]

I calibrate the same way I test. Wash off the refractometer with fresh water. Dry the refractometer. After 4-6 drops of tank water I slide my finger down the cover. Excess liquid drips off then I wait 45 seconds before taking final reading. If I'm doing something please tell me. I think the temperature of the calibration solution should be consistent with your tanks water too.

 

[bif24701]

I calibrate the same way I test. Wash off the refractometer with fresh water. Dry the refractometer. After 4-6 drops of tank water I slide my finger down the cover. Excess liquid drips off then I wait 45 seconds before taking final reading. If I'm doing something please tell me. I think the temperature of the calibration solution should be consistent with your tanks water too.

Sounds good to me.

 

[Epicreefster]

I would trust the calibration solution over RODI but funny story, about two months ago we double checked the aquacraft calibration solution on the basically new milwaukee digital refractometer I keep boxed up on a shelf and following milwaukees instructions for calibration, with distilled sample they provided, then double checking with their 35ppt solution, the aquacraft tested at 1.028. So again calibration either refractometer with RODI/distilled came up with aquacraft being high. I personally would trust milwaukee instruments solutions over aquacraft.

When it comes to salinity for a reef tank you can realistically run from 1.023 to 1.028 and be fine, but lower provides more room for error, and with evaporation you are always going to go up in salinity if something odd happens like you run out of top off water. If you want a true reliable reading with no room for error invest in a glass hydrometer calibrated at 75 degrees and save the instructions for temperature compensation. Once you get the spinning down to remove microbubbles and are comfortable reading it its easier than a refractometer, but fragile. We just switched to salifert calibration solution and run our systems lower than NSW for a variety of reasons so were not to picky on perfection.

 

[RainboWBacoN420]

Took a sample into work today and tested my salinity on a digital Refractometer and the results gave me 1.024. So i think the calibration fluid is accurate. I cant believe I had it wrong this whole time.

 

[jason2459]

Relevant thread:
http://reef2reef.com/threads/does-your-calibration-solution-need-calibrated.250133/

And for those that live around south Florida the salinity off shore there on the bayside and ocean sides fluctuates quite a bit seasonally and possibly daily. This can be looked up and through personal experience.

See if this works. It's to a pdf
https://www.google.com/url?sa=t&sou...0TTBw26EK9IMJADwg&sig2=o2wpI7ImogmgzHhwPcC2sw

 

[Valkyrie]

I use a refractometer at my job every day, you should not be pressing down on the cover. I know it doesn't look like much, but a refractometer is, in fact, a delicate piece of scientific equipment. :)

 

[Valkyrie]

I calibrate the same way I test. Wash off the refractometer with fresh water. Dry the refractometer. After 4-6 drops of tank water I slide my finger down the cover. Excess liquid drips off then I wait 45 seconds before taking final reading. If I'm doing something please tell me. I think the temperature of the calibration solution should be consistent with your tanks water too.

Truthfully, you only need one drop of water, two at the most. No reason to wait, either.

 

[jason2459]

The tip of south florida seeing some of the extremes as coming through the entire bottom half of Florida for the most part are two very slow moving troughs or wide rivers. Canal structures have created some issues with it as well. Used to be able to find quite a lot of freshwater springs out in the bay and ocean from water being pushed through. Manatees took major advantage of those as did sailors way back in the day.

 

[PureReefSystems]

One note to improve calibration is to match temps with solution and tank water.

 

[jason2459]

One note to improve calibration is to match temps with solution and tank water.

I would not worry as much about this unless one of them are at an extreme. The small amount of water once placed over the prism would change temp quickly anyway. I would give some time for the ATC to take place.

 

[jason2459]

I use a refractometer at my job every day, you should not be pressing down on the cover. I know it doesn't look like much, but a refractometer is, in fact, a delicate piece of scientific equipment. :)

Very true. It doesn't take much to be taken out of calibration. A simple bump or just being used over time as the bi metalic strip wears and needs recalibrate. Some refractometers are more prone then others.

Truthfully, you only need one drop of water, two at the most. No reason to wait, either.

I would wait to give the ATC time to react.

 

[LXM26]

How about an auto top off.. ??

 

[Valkyrie]

I would wait to give the ATC time to react.

Refractometers don't "react", they measure how quickly light travels through a liquid. Waiting accomplishes nothing. I can take a reading right away or 5 minutes later, it doesn't change anything unless there's been enough evaporation to change the concentration of the liquid. Which, of course, would result in an inaccurate reading in itself. :)
The only thing you need is the refractometer, the liquid you're measuring, and a light source.

 

[jason2459]

Refractometers don't "react", they measure how quickly light travels through a liquid. Waiting accomplishes nothing. I can take a reading right away or 5 minutes later, it doesn't change anything unless there's been enough evaporation to change the concentration of the liquid. Which, of course, would result in an inaccurate reading in itself. :)
The only thing you need is the refractometer, the liquid you're measuring, and a light source.

If you don't have an ATC on your refractometer then you are correct and immediate readings should be done with the samples brought to the recommended temperature of the refractometer.

However, with a refractometer that supports ATC there is a reaction to the temperature of the solution placed on it. It can be seen if viewed immediately and continue viewing watching the line drift slightly. On veegee or vitalsine this is much easier for me to see as its a nice bright viewer and distinguished line.

 

[Valkyrie]

Actually I use both.

 

[Randy Holmes-Farley]

Refractometers don't "react", they measure how quickly light travels through a liquid. Waiting accomplishes nothing. I can take a reading right away or 5 minutes later, it doesn't change anything unless there's been enough evaporation to change the concentration of the liquid. Which, of course, would result in an inaccurate reading in itself. :)
The only thing you need is the refractometer, the liquid you're measuring, and a light source.

As Jason pointed out...... Just to clarify the mechanism, and while the response is fast, the ATC aspect of a refractometer is a reaction of the bimetal strip to temperature changes. It changes size as the temp changes. So it does "react" to the temperature of the refractometer and liquid. :)

 

[stevo01]

Thanks. I'll recalibrate my refractometer and test do my tests without interfering with the cover from now on. I'm still on the fence as to applying a gentle swipe over the cover will throw anything out of whack, but I'm always up to try new things. I think more people should be more open minded about trying new things in general.

I'll report back with what the actual difference is in readings.

 

[jason2459]

As Jason pointed out...... Just to clarify the mechanism, and while the response is fast, the ATC aspect of a refractometer is a reaction of the bimetal strip to temperature changes. It changes size as the temp changes. So it does "react" to the temperature of the refractometer and liquid. :)

Yes, and some time does not have to be a long time. [emoji4]

I believe I did state somewhere above temp change can happen quickly with such a small sample of water.