Calibrating Refractometer

[Jblaine]

I am new to saltwater tanks and have had one running for 5 weeks now. Recently I purchased Brightwell calibration solution and tried to check my refractometer with it. I let it sit for a minute and set the blue line to 35ppt. Then when I rinsed it with RO water, the blue line was way below zero. Can someone help me with what’s going on? I’ve even rinsed the refractometer glass and cover and off several time to make sure it was free of salt and it still does the same thing. I want to make sure my salinity is ok.
Thanks
Jon

 

[Spare time]

I believe they are also temperature sensitive. Try checking it compared to your hydrometer (assuming its an ok brand). Have a bit of ro water sit in a container till its 78 degrees like the tank and then check. I am not sure why they are sensitive to temperature but it is my understanding that they are

 

[Jblaine]

I believe they are also temperature sensitive. Try checking it compared to your hydrometer (assuming its an ok brand). Have a bit of ro water sit in a container till its 78 degrees like the tank and then check. I am not sure why they are sensitive to temperature but it is my understanding that they are

Ok thanks I will try it