Broken refractometer??

[Jay1982]

For a year and a half my salinty has been stable at 1.025. I noticed some SPS seemed to be losing colors so I checked all my parameters and everything was ok until I saw my salinity at 1.019. I freaked and started making water right away. I checked my levels the week before and it was at 1.025 and nothing dramatic has happened in the last week to cause such a discrepancy. Anyways, I checked my prepped water and I dumped half a bag of reefcrystals (the kinda that makes 50 gallons worth) into 2 home depot buckets and my salinity is only at 1.015. What's the deal? it should be waaaaaaaaay higher!!!! Do refractometers de-calibrate over time?

[PRDubois]

Calabrate with RODI to 0.0
Refractor should have come with a little screwdriver. You turn the screw to calibrate it

[Jay1982]

I put some RODI and its at 0. How do I know its calibrated?

[PRDubois]

You just did!
If RODI reads 0 then it is calibrated properly.

I use 11 cups of RC salt mix for 20 gal of water.
Must salt mixes will say 1/2 cup per gal. That will not give you 1.025 it will give you normally 1.021

[Jay1982]

Nice, thanks man!!!

[paraletho]

Has the refractometer been dropped recently the mirror inside is set at a certain angle. If that angle changes it is possible to have a calibrated unit at the low end and off on the high end. It is best to check both using a known 35 ppt or 53.1 microsiemens and a 0 point.

[HotHotHot]

^^^ What he said. PinPoint makes the appropriate calibration fluid.

My refractometer seems to drift out of calibration regularly.

[Tswifty]

Don't use RO/DI water. Use the PinPoint calibration fluid. I usually calibrate my refractometer once a month to make sure it's accurate.

[abulgin]

<a href=showthread.php?s=&postid=15255446#post15255446 target=_blank>Originally posted</a> by Tswifty
Don't use RO/DI water. Use the PinPoint calibration fluid. I usually calibrate my refractometer once a month to make sure it's accurate.

+1

[Jay1982]

I'll see if I can find some around here. But something crossed my mind yesterday, if the refractometer is reading below the actual salinity level and I go to use whatever calibrating liquid to correct it, how do I know its calibrated?? At reading 0.0 its just reading the lowest possible reading.

[snorvich]

<a href=showthread.php?s=&postid=15253899#post15253899 target=_blank>Originally posted</a> by PRDubois
Calabrate with RODI to 0.0
Refractor should have come with a little screwdriver. You turn the screw to calibrate it

that is not right. Calibrate with a standard solution such as Pinpoint solution which is 1.0264

[J's Quiet Reef]

Yes, definitely calibrate with the Pinpoint Solution. I had trouble with a fish in hypo because I thought calibrating w/ ro/di water was good enough. I raised the salinity until I was able to get some calibration solution. When I checked it with the solution, the refractometer was off by .002