Problem with refractometer

[Doreno]

Hello,

I cant understand why, but each time when I trying check my salinity I have different measurement values on timelaps 10min, 32ppm next measuring 34ppm, measurements after 5 minutes already shows 33 etc.

 

[Alchameth]

What's the temp of the water? Think most should be tested around 77deg, so if your water is colder than that wait about 30 seconds after you put the water on to take reading. Also you should be cleaning it with RO water and dry it with a soft cloth after use, if you just wipe saltwater off some residual salt could stay on the glass and throw off readings. Lastly you can check it with RO water and make sure it reads at 0.

 

[Doreno]

I have 25C water temp, but before testing, I get water to small bottle to make test in other room than the tank placed, and make test after about 5 minutes after taking water from the aquarium

 

[Snoopy 67]

There is an adjustment screw on most refractometers, make sure it is tight.
Your model should be ATC, automatic temperature compensated.
Use a calibration fluid to double check the salinity of the unit.

 

[Alex808]

I check and calibrate my refractometer pretty often. Just to make sure. I think the liquid I bought on amazon was like 6 bucks?

 

[Emptyness]

Do you calibrate it before testing? Before every test I use RO water and make sure that the refractomer is actually reading 0 and then I wipe it off and put the salt water.

 

[Alex808]

Do you calibrate it before testing? Before every test I use RO water and make sure that the refractomer is actually reading 0 and then I wipe it off and put the salt water.

Depends. Sometimes I do it before. Sometimes I do it after. Sometimes both. I keep my tank mostly covered and my ATO doesn’t come on super often so I double triple check. I started reefing with a 5g and now have a 20 long. Ive seen the salt swing pretty fast so I calibrate often for my peace of mind. Calibrate regardless if you think you’re reading correctly.