salinity question

[Nano]

Originally Posted by Cal_stir

you can get calibration fluid, i would bet the refractometer is correct, my deep six hydrometer was out 4 points, it was reading 1.023 when actual was 1.027, my snails stopped dying after i corrected the salinity.

mine too lol. poor little buggers. haha, thats why I'm glad I know how much my hydrometer is out, and glad to know I'm getting a refractometer for xmas

[sphelps]

RO water at the same tank temp should read zero on the refractometer, if it's not adjust it with the screw driver typically provided. They usually need to be calibrated as salinity is temperature dependent.

[fishytime]

Originally Posted by sphelps

RO water at the same tank temp should read zero on the refractometer, if it's not adjust it with the screw driver typically provided. They usually need to be calibrated as salinity is temperature dependent.

Um, don't you mean distilled water Steve?...... I wouldnt callibrate a refractometer with RO....but that's just me I guess

[sphelps]

Originally Posted by fishytime

Um, don't you mean distilled water Steve?...... I wouldnt callibrate a refractometer with RO....but that's just me I guess

Wouldn't bother myself, if you want to go through that much trouble it's up to you but I put money on it not making a difference. Pretty much everyone has RO water on hand and realistically you're interested in the change of salinity from your source water and mixed saltwater plus if you're off by a tenth of a percent it won't mater, acceptable salinity is pretty big range, consistency is more important. My tank does just fine using a refractometer calibrated with RO.

[fishytime]

well if you have an RO unit and are sure of the TDS, then maybe........but I wouldnt trust the store bought RO or the Culligan man for having a low TDS

[babyreef]

BLANK

[fishykisses]

i took my water and refractometer in, got it calibrated...it was one point off and all is well.
my hydrometer was way off.

[sphelps]

Originally Posted by fishytime

well if you have an RO unit and are sure of the TDS, then maybe........but I wouldnt trust the store bought RO or the Culligan man for having a low TDS

Not to get technical but your refractometer measures salinity in ppt (parts per thousand) so even if your RO water was way out at 35ppm (parts per million) you'd still only be out by 0.035 ppt on your refractometer. Accuracy on a scale measured by your eye is equal to +/- half a mark which in the case of all the refractometers I've seen is 1 ppt, so you're refractometer even if calibrated perfectly is technically only accurate by +/- 0.5ppt. I wouldn't worry about that extra 0.035ppm, you couldn't even tell the difference when you calibrate it.

[Myka]

Some salinity tips from Randy Holmes-Farley: http://reefkeeping.com/issues/2006-12/rhf/index.php

Fwiw, my hydrometers are out by 0.007 and 0.008.