time to recalibrate

[daisy]

yes, that is precisely what it was called. ...wonder whose sense of humor that was ;-P

 

[Simon Garratt]

Simon, darling - If you are brave enough and have enough time to get lost again, I'll be happy to drive you around in Orlando!

Ohhh....i just got goosebumps....:shhh:

 

[regal]

Mine was off by about 4 parts per million, which makes a HUGE difference in the life of many corals.

I think you meant 4 parts per thousand (ppt) and if it is, that is a big difference. But 4 ppm, I think not.

 

[daisy]

I was not paying attention to the units. sorry.

 

[Chris Jury]

You can also use the Pinpoint calibration fluid, which is available lots of places (e.g., see here http://www.bulkreefsupply.com/store/pinpointr-salinity-calibration-fluid.html). It has a conductivity like that of seawater at 35 ppt as well as a refractive index of seawater at 35 ppt.

Conductivity and refractive index don't vary precisely with salinity in all solutions. As Simon alludes to above, seawater with a salinity of 35 ppt has a *different* refractive index from, for example, a solution of NaCl at a salinity of 35 ppt. The calibration fluid above works, and you can make your own calibration fluid if you can measure mass/volume accurately, but you CAN'T put 35 g NaCl in enough water to make 1 L and get the correct refractive index. See here for a DIY standard: http://www.reefkeeping.com/issues/2004-06/rhf/index.php