Calabrating Refractometer

[DarkHorseMBA]

I've been using distilled water to calibrate my Refractometer, assuming that the water should read 0.

Is this okay?

DarkHorse

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[Big_Pun]

i dont think distilled water is at zero, they sell calibrating solutions from buckeye and bulk reef supply

[fishypets]

Do not use RO/DO or distilled water to calibrate your unit. Instead use calibration fluid, which calibrates the unit to 35ppt or 1.0265. I used ro/di for a while and lost a bunch of coral due to hypo-salinity. It was off 5 ppt! YIKES

[DarkHorseMBA]

Ok did my own test and here's the scoop.
Used a reference liquid from fosters and smith, read 35ppt perfect.
Used distiller water and it read 0ppt.
So distilled water works fine no need to spend $8 on calibration fluid.

DarkHorseMBA

[hclchicken]

Qualifications: I actually use these in my job and calibrate them with multiple solutions. In my job they are used to test SG of urine and is regulated by CAP (college of american pathologists).

As long as your reference fluid is accurate, then you can use it to calibrate. Your RO/DI should be pure, but might not. Ideally your refractometer shouldn't change day to day, but it can. Ideally you want to batch make your RO/DI water, then measure it and bottle it in a glass bottle so that the value doesn't change.

Get your LFS and yourself to make sure the RO/DI has nothing in it to verify. Once that value of water is measured and you have the true value you can pull from that bottle as often as you need. Don't pull from your RO/DI device as that value can change day to day.

In my job we use a calibrated solution of Saline water, pure water and two different urine specimens with calibrated values.

for the quick answer- IF you know the TRUE value of the solution SG, then you can use whatever you want.

[ramsey]

Ok did my own test and here's the scoop.
Used a reference liquid from fosters and smith, read 35ppt perfect.
Used distiller water and it read 0ppt.
So distilled water works fine no need to spend $8 on calibration fluid.

DarkHorseMBA

You should use both. It can still be off when just using distilled water. Here's a URL that better explains why:

http://reefkeeping.com/issues/2006-12/rhf/index.php