Calibrate your Refractometer

techdiver · 07/19/2012, 03:38 PM

I had company coming in for the weekend, so I didn't want to have salt buckets out mixing when they arrived. So I went to BSL and bought mixed 1.025 saltwater. Out of habbit, I checked the water with my refractometer and it showed 1.027. I thought they were off a bit on the mix, but I decided to check the calibration on my Milwaukee and it was off by .002. That doesn't seem like much, but I was generally running mine at 1.023 since I do not currently have a topoff. That means I have really been at 1.021 and explains why some coral was not too happy and growth had slowed. After the calibration and slowly correcting the salinity, the coral looks much healthier.

Refractometers are the way to go as they are much more accurate than hydrometers if they are calibrated.

At least I caught it before a disaster.

You can calibrate the instrument with a set salinity solution packet or you can just use RO/DI water and set it to 0. You should have a precision screw that is used to accomplish this. Mine had a cap over the adjustment screw.

Take care,
Tech Diver

Below Sea Level · 07/19/2012, 06:12 PM

Good advice. It is an easy thing to forget about after a while.

05grandprix · 07/19/2012, 08:49 PM

I need to get to bsl to get water

07/19/2012, 03:38 PM	#1
techdiver Registered Member Join Date: May 2009 Posts: 1,401	Calibrate your Refractometer I had company coming in for the weekend, so I didn't want to have salt buckets out mixing when they arrived. So I went to BSL and bought mixed 1.025 saltwater. Out of habbit, I checked the water with my refractometer and it showed 1.027. I thought they were off a bit on the mix, but I decided to check the calibration on my Milwaukee and it was off by .002. That doesn't seem like much, but I was generally running mine at 1.023 since I do not currently have a topoff. That means I have really been at 1.021 and explains why some coral was not too happy and growth had slowed. After the calibration and slowly correcting the salinity, the coral looks much healthier. Refractometers are the way to go as they are much more accurate than hydrometers *if they are calibrated*. At least I caught it before a disaster. You can calibrate the instrument with a set salinity solution packet or you can just use RO/DI water and set it to 0. You should have a precision screw that is used to accomplish this. Mine had a cap over the adjustment screw. Take care, Tech Diver __________________ Jackson Area Reef Club

07/19/2012, 06:12 PM	#2
Below Sea Level Premium Member Join Date: Jul 2005 Location: Jackson, TN Posts: 349	Good advice. It is an easy thing to forget about after a while.

07/19/2012, 08:49 PM	#3
05grandprix Registered Member Join Date: Aug 2010 Location: Cedar grove ( Lexington side ) Posts: 625	I need to get to bsl to get water