Always double check those refractometer readings!

[Turtlesteve]

... A 25% water change with SG = 1.015 instead of 1.025 makes for a really bad couple of days.

Been doing this quite a while, but it's the first time I've made that mistake.

Steve

 

[cody6766]

I always rinse the flap and lens with tank water, wipe it clean and then take my reading. I check it a second time just to be sure and check it a third time if there is a difference between the first two.

 

[2_zoa]

Since I purchased calibration solution I use it before I take a reading. I give each a minute on the lense before I I take the reading with a rinse in between.

 

[Fourstars]

Yep! And check the tank salinity not just the make up water, it tends to creep up.

 

[EMeyer]

I always rinse the flap and lens with tank water, wipe it clean and then take my reading. I check it a second time just to be sure and check it a third time if there is a difference between the first two.

Yes, exactly this.

My practice:
1. check calibration at each use with a 35 ppt standard solution
2. discard the first reading of my sample (effectively rinsing off the salt like you describe)
3. Take 2-3 readings of my sample

I am convinced the hobby is plagued by inaccurate salinity readings and I have seen lots of evidence that small salinity deviations are very bad for corals (and cuttlefish). Fish dont care.

 

[jd371]

Yes, exactly this.

My practice:
1. check calibration at each use with a 35 ppt standard solution
2. discard the first reading of my sample (effectively rinsing off the salt like you describe)
3. Take 2-3 readings of my sample

Pretty much my routine as well.

 

[Turtlesteve]

No instrument error in this case....I just plain read it wrong. I check cal before and and typically take at 2 readings. I'm visually expecting the line to be exactly halfway between the bold lines indicating 1.020 and 1.030 s.g. - and it was halfway between 1.010 and 1.020.

Steve