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Calibrate your Refractometers Occasionally!


tinyreef

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first, i'd like to say that refractometers are an essential tool for nano-reefing imo.

 

while i don't like being so definite about such opinions since there are always more ways than one to skin a cat (and i have receipes if you like) but due to the small volumes we deal with versus traditonal tanks, small discrepancies can be disasterous and the accuracy of refractometers (vs. hydrometers) allows us to maintain that tight tolerance.

 

that said, everything still needs a little maintenance and work now and then. i just (re)learned that lesson today. thankfully without any major disasters, yet.

 

i'd been noticing my office nano (15H w/5g sump) being a bit "sluggish" in the past couple of months. i just chalked it up to lack of attention (work, pico contest, family, etc.). so i finally do a waterchange today (about 10%, which is a lot for me) and check the salinity with my office refractometer (i keep another at home), reads 1.022. a bit low but not crazy as i'm wc'ing and can adjust that on the fly. but for some odd reason i just didn't like/trust the reading today.

 

so i doublecheck it against my ro/di water and it turns out my refractometer's scale is off around 0.008! :blink: i.e it's reading 1.008 with pure water where it should be 1.000. <smacks-forehead!>

 

i doublecheck, triplecheck, quadruplecheck, and actually just quintplechecked with the home refractometer (yeah, anal) but it still reads off. so i re-calibrate with the ro/di and check the tank.

 

a brisk 1.016, ugh.

 

panic sets in about now omgomgomg but i push it aside, probably because i'm still in shock. i "dose" a super-briney/salty mini-batch to push it up to 1.018 for now. i'll probably adjust it slowly back up to the 1.023~1.024 range that i prefer over the next couple of days. *sigh*

 

at least now i know why the tank's been looking a bit glum. the fish was happy though. dumas fish.

 

so just a word of advice, use refractometers but doublecheck them (with pure water) every now and then.

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first, i'd like to say that refractometers are an essential tool for nano-reefing imo.

 

i agree.

 

i haven't used my super expensive refractometer ($100+ :o) in a long time. i trust the NSW to be on mark.

 

when i did use it, i calibrated before every use even though it never really needed it. calibrate frequently!

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check the salinity with my office refractometer (i keep another at home), reads 1.022. a bit low

 

...er...uh...you checked your specific gravity...if you checked your salinity the number would be a percentage...picky, I know, but, good to get terms correct. SH

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...er...uh...you checked your specific gravity...if you checked your salinity the number would be a percentage...picky, I know, but, good to get terms correct. SH
picky picky picky.

 

ok, i read the numbers on left of the scale for the specific gravity which reads in the ranges of 1.000 to 1.040, which corresponds to the salinity scale on the right. which should be in the 32~36 ppt range, depending on preferences. ok, dr. steel?

 

 

 

see? now you've gone and confused the newbs. i hope you're happy.

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so i doublecheck it against my ro/di water and it turns out my refractometer's scale is off around 0.008! :blink: i.e it's reading 1.008 with pure water where it should be 1.000. <smacks-forehead!>

 

Unless you calibrated with distilled water your readings dont mean anything.

 

Any lab in the country who uses refractometers for scientific measure uses a "calibration fluid" for testing specific readings, but all are calibrated with distilled water...its the only thing that will give you a pure 1.000 reading.

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thanks for the heads up. i have distilled water for drinking so ill callibrate mine pretty often.

 

 

Yeah..use distilled. I wouldnt want anyone calibrating falsely and having bad results because of it.

 

Been there, done that!

 

:)

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Yeah..use distilled. I wouldnt want anyone calibrating falsely and having bad results because of it.

 

Been there, done that!

 

:)

How is commercially available distilled water "better" for calibration than RO/DI water? If we are going for purity of the H2O then shouldn't a good RO/DI system be just as good or even possibly better?

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How is commercially available distilled water "better" for calibration than RO/DI water? If we are going for purity of the H2O then shouldn't a good RO/DI system be just as good or even possibly better?

 

RO/DI water is produced by the physical action of water being pushed through a membrane and then having further impurities removed by being bound to a resin. There is always the chance that some particles will be squeezed through the membrane and water that doesnt come in contact with the resin will not have particles removed.

 

Distilled water is made by having the water heated to boiling and then the water vapor passes through a series of coils where it is slowly cooled and collected, leaving all of the impurities behind in the heating vat. This is often done twice, sometimes more for laboratory uses.

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