Calibrate refractometer (1 Viewer)

[angel4]

Recently I bought some fish from the LFS and found out that when their refractometer says 1.025, mine would read ~1.027.

My refractometer came from Marine Depot pre-calibrated and I used it to check the RO-DI water I have straight out of the filter and it says 1.000.
I know my TDS meter reads ~20 ppm.

Should RO-DI water reads 1.000 with refractometer ?

 

[AquaNerd]

calibrate with distilled water.

 

[angel4]

Refract

Hmm, isn't RO-DI distilled water?
If not, where do I get distilled water? Not from a supermarket, I imagine?
The water from a supermarket's filter can not be purer than what comes out of our own, can it?

 

[Guest]

They say the best way is to make a 35pt solution to test with. Either make it with the recipe over on RC or buy some. I think it called Pinpoint 35pt solution or something like that. Of course this is the over cautious, over the top way of doing things as with most things we do with our tanks.

 

[GAW]

I did mine last night and it came o with my RO water

 

[stdreb27]

The reality is you could calibrate it with tap and you wouldn't notice a difference. I'd lean towards the LFS's refractometer being out of calibration...

 

[Guest]

angel4, camaroracer means calibrate it with distilled water so that you can rule out any issue with your RoDi unit.

Also, what does your LFS's refractometer read for RoDi water?

 

[Guest]

I use pinpoint 35pt to calibrate mine.

 

[Timanator]

how often do you have to calibrate the refracto's? While we are at it, how much does variations in salinity affect the health of your tank. Cause I havnt noticed much!!!

 

[stdreb27]

typically I'll check it when I test the water.

 

[angel4]

Re: Refract

Hmm, was I slow ?!
I could boil some water and catch the water vapor. That should be a good source of distilled water.
I've been out of school too long

 

[Rick]

Any grocery store has distilled water.
Usually by the bottled water.

 

[Guest]

I check whenever I feel the need.

Sometimes there's a drastic difference from checking with a hydrometer and a refractometer. I know cause I bought some sw that was suppose to be 1.025 on a hydro. but my refracto caught it at 1.019.

That would have stressed my fish out some.

 

[angel4]

Refracto

The reality is you could calibrate it with tap and you wouldn't notice a difference. I'd lean towards the LFS's refractometer being out of calibration...

This turns out to be true.
I calibrated my refracto with tap water, distilled water (water vapor which I boiled) and my RO/DI water and they all came out very close. Could hardly tell the difference.

 

[stdreb27]

Re: Refracto

The reality is you could calibrate it with tap and you wouldn't notice a difference. I'd lean towards the LFS's refractometer being out of calibration...

This turns out to be true.
I calibrated my refracto with tap water, distilled water (water vapor which I boiled) and my RO/DI water and they all came out very close. Could hardly tell the difference.

I really can't. Maybe .001 difference. Which is smaller than the swing I get between topoffs. I'm not advocating using tap. I use RO/DI but it really isn't the life or death situation if you use ro/di or distilled water or calibration fluid, that some make it out to be.