Refractometers & temperature

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CenlaReefer

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I am using a traditional ATC refractometer yet noticed some problems that was worse because of my doing a water change in my sunroom during the winter. I have been keeping a reef tank since about 2011 and I am still learning so much. This ordeal was humbling.

My readings for my salinity were too high both for my sunroom system and for my newly mixed SW today. I kept cleaning the refractometer using a quick dip into a bucket of RO to rinse it and then dry it off with 100% cotton. The readings kept getting higher the more I re-tested. I was so confused. I called my brother who told me before about cold temperatures throwing the tests off. After that conversation, I realized that my rinse-dips were in very cold RO water and the refractometer was getting increasingly colder because of the dips. Recalibration did not help. Once I brought the device to room temp and then recalibrated it again using my calibration solution, the readings were normal.

Here is my plan from now on:
(1) I will keep the device in its case and then inside my coat pocket to keep it warm before testing. I will also make sure it feels room temp and not cold.
(2) I will rinse the refractometer between tests using a pipette and room temp water. Maybe I will use a squirt-bottle. I will only do a rinse-dip before putting the device away.
(3) Do water changes when weather is moderate or warm only.

This problem has me more interested in something like the Milwaukee digital refractometer. I am curious about what you all think of those units.
 

BluewaterLa

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Testing the tank should be no issue, just let the refractometer temp acclimate for a few moments then read
When testing water from your mixing container if it not heated, Take a cup into a warmer part of your home and allow it to sit for a few hours before testing.
Had to deal with this issue when my RO and mixing container was in my garage in the winter months. Severe cold water will throw them off at times but allowing it to acclimate to temp is best. Once had a refractometer that was really good at giving accurate results no matter the water temp.
I find my digital SG pen works well in all temperature ranges, There does come a point when temperature will throw off your testing for SG by a couple of points on both the warm and cold ends.
This makes sense to mix and test at the same temps as your display tank for most accurate results.
 

CenlaReefer

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I find my digital SG pen works well in all temperature ranges, There does come a point when temperature will throw off your testing for SG by a couple of points on both the warm and cold ends.
Which digital SG pen do you have? I was amazed to find such a good price for a SG pen on Amazon. The ratings are great for this one below; however, I didn't read any reviews yet from people using it for saltwater reef tanks.

Digital Salinity Tester for Salt Water - Waterproof IP67 Salinity Meter with ATC Large Range 0-200ppt Saltwater Tester for Seawater, Aquariums, Marine Monitoring, and Koi Fish Pond by ORAPXI https://a.co/d/0JaOJNv
 
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CenlaReefer

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Regarding the above tester, I read this one bad review:

"This doesn’t convert to example (1.025) specific gravity. It gives you the ppt or ppm and then you have to google the conversion table to get your salinity. Go with the Hanna checker and spend the extra $30."

On BRS one customer recommended the Hannah digital SG tester over the Milwaukee.
 

CenlaReefer

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I purchased the Milwaukee from @The GOB. Thanks again, Jordan! I am crazy busy until Sunday evening. I plan to try it out for the first time then. So cool!
 

CenlaReefer

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I do love using the Milwaukee digital refractometer! It is so easy to use. I like that it has built in temperature compensations to give accurate readings. Calibration to "zero-out" the unit with distilled water is rather simple and quick.

@The GOB, thanks much for the good deal and for going through the trouble to ship it for me.
 

clsanchez77

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I was going to say that if you don't purchase the Milwaukee now, you can always recalibrate the other one at the current temperature...just remember to calibrate it yet again when temps warm up.
 
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