How often do you calibrate your refractormeter??

[jhj0112]

I have used have my refractormeter for nearly a year (10 months) and never thought of calibrating it because it seems to work well..

How do you know it's time to calibrate or how often do you calibrate it??

on google, some says they calibrate every time you use, others say they have not calibrated it for over 2 years..

[Coral Hoarder]

mabie once a year it seems to stay perfect tho

[Slyguy00]

every few water changes i check it.. Once a year scott? really, come on man lol

[Coral Hoarder]

Lmao or when my corals look funny and everything thing elts checks out :p

[Aquattro]

People calibrate these things?? oh....lol

[jhj0112]

People calibrate these things?? oh....lol

haha that's what I thought at first.. lol

[Flash]

I don't do many water changes.... But once ever few months! Lol it only takes a second!

[Aquattro]

But once ever few months! Lol it only takes a second!

Ya, but that little bottle of calibration fluid dries up the first week :)

[Flash]

Lol oh it's been a long time! I forgot how much fun this site was!

[lastlight]

Never have maybe I should check it lol.

[Myka]

I check mine about once a month. I check my clients' refractometers about once a month too. I find they all can use an adjustment by that time.

[mikellini]

I've read that light and temperature both have an effect on accuracy. For instance, if you're checking specific gravity on your water change mix in relation to your tank, you'll want to do it at the same temperature (unless you adjust for the difference) and definitely with the same light source.

It's probably more important to be accurate if you're running at 1.026, but if you run at 1.025 you have a bit more margin for error.

[Aquattro]

I've read that light and temperature both have an effect on accuracy.

I've tested the same water in kitchen under 100w lighting and against 800w of MH, same reading. And both my units are ATC, so temp shouldn't be a factor either.

[kamloops_reefer]

everytime - I have a vertex one and find that its a pretty touchy instrument. and can fluctuate +/- 0.03

[mikellini]

I've tested the same water in kitchen under 100w lighting and against 800w of MH, same reading. And both my units are ATC, so temp shouldn't be a factor either.

From another forum (Randy Holmes-Farley, don't know if I can post the link):

------------------

I was recently asked whether the light impacts the results one gets with a refractometer.

I'll give the rationale below, but it turns out it is CRITICAL that you use the same color light for calibration as for measurement. Don't move to a different room of your house where the lights may be different.

The reason for this is that the refractive index of water (fresh or salt) changes a lot with wavelength. The standard for all visible light refractive index measurements is supposed to be yellow (specifically, the yellow doublet sodium D line, with a wavelength of exactly 589 nanometers), but reefers rarely worry about such complexities.

The link below shows how much the refractive index of pure fresh water changes with wavelength (color):

Refractive index

specifically, here's a graph:



Look, for example, at the difference between deep blue (say, 480 nm) and orange (about 650 nm). Let's look at just the light blue line. That difference, from about 1.339 to 1.3325 is, remarkably, about the same as the difference between pure fresh water (RI = 1.33300) in yellow light and natural seawater (1.33940) in yellow light.

So the color effect on refractive index is as large as the entire difference between salt and fresh water.

However, we have a big saving feature at work. As long as you calibrate and measure in the same light (same color), the overall effect of the change in refractive index with light color largely cancels out between the calibration and the measurement, and you are able to sort out what portion of the effect comes from the added salts in the aquarium.

What you cannot do is calibrate under one type of light, and then measure tank water under a different set of lights (for example, in a room with fluorescents vs a room with incandescent lights or outside, or in a basement and then next to a tank with a lot of blue light.

Of course, rarely would someone have such extreme light differences as the deep blue vs orange mentioned above, but that is a 100% error in the salt concentration (ie., salinity might be really 1 ppt or sg = 1.001 when the refractometer says 35 ppt or sg = 1.026). I assume most reefers would like the salinity measurement to be far, far better than that, and so paying attention to the color of the light within the range aquarists might actually encounter is important.

So be sure and calibrate and measure in the same location if using a refractometer!

--------------

And yes, theoretically if you have an ATC refractometer and it's working correctly, then you shouldn't have to worry about temperature. But if your refractometer is down in a cold basement, you might want to keep it upstairs just in case and bring it down to measure.

[mikellini]

everytime - I have a vertex one and find that its a pretty touchy instrument. and can fluctuate +/- 0.03

My vertex unit is touchy too. I calibrate with a 35ppt solution every time.

[Nicole.]

I never calibrated mine since the day I first got it which was prob a couple years ago...big mistake. Just recently had a buddy test my water and it was at 1.022 even though it would show as 1.025 on my refractometer. Who knows how long it's been at 1.022??! I've had a bunch of nice corals die and gave up on them because I couldn't figure out why at that time... Now I will calibrate mine after a couple uses. A bottle of proper calibration solution is only $5 so it's worth it.

[Slyguy00]

My vertex unit is touchy too. I calibrate with a 35ppt solution every time.

I'm with u guys. Pretty simple to keep calibrated so why not? The less fluctuation my tank sees the happier it will be as far as I'm concerned.

[jhj0112]

hmm maybe it's time for me to calibrate mine....

[SteveCGY]

Once every two years considering I use it once a month. And always leave it a point high so it compensates for evaporation and never let more than 4l absolute max evaporation. As soon as I can see water under my trim I add and add calcium to rodi water I ad

[Myka]

everytime - I have a vertex one and find that its a pretty touchy instrument. and can fluctuate +/- 0.03

Yeah, I find the Vertex ones are pretty bad for wandering.

[Dearth]

I calibrate my vertex when I think about it which is once every month or so.

[kamloops_reefer]

you wouldn't think that a name like 'vertex' would offer a product which sounds more touchy than others?

Perhaps I'm just too rough on precision tools - but if I calibrate mine (I use the solution as well) and then set it down on the table a couple times (about as diligent if it was a glass of water, so not too gentle, not too rough) you might be surprised to find that it will change on you.

I usually have to calibrate the unit twice, first time could have left over residue from previous testing on the glass. Second is a for sure check - and as well as the tank water, check twice or even three times, trying not to set it down or bump it into anything (I usually just dip the entire end of the Ref. into the tank)

[shiftline]

Never.. Every once in a while o check it with RO. Never rally seems to change calibration on me

[Reef Pilot]

I checked mine a few times initially, but it never changed, so have not checked it for at least a year now. Maybe I should...

[Madreefer]

Never....I haven't checked salinity in years.

For those of you who do check, what do you use to calibrate? Here in PG we don't have a source of SW supplies.

[lastlight]

this is looking like a new years resolution i can handle...

[whatcaneyedo]

I've been calibrating my Sybon annually for a few years with calibration solution from J&L. It generally doesn't change by much unless I bump or drop it.

[mikellini]

Looks like I'm in the market for a new refractometer. Suggestions?

[Reef Pilot]

Looks like I'm in the market for a new refractometer. Suggestions?
Sybon.

[Reef Pilot]

To satisfy my own curiosity, I just tested my Sybon again. It was dead on with both the 0 ppt and 35 ppt calibration solutions. I went out and bought the 35 ppt solution the last time we had this fear mongering on the forum.

I have owned it now for over 4 years (use it before and after water changes) and have never had to calibrate it.

[lastlight]

maybe it's the bumping some people do? I handle mine like fine china just out of habit. I plan to test to satisfy my curiosity but I will be shocked if it's not still accurate.

[The Guy]

I have a Sybon and every time I've checked it it's always bang on. Had it 2 years now and have only checked it maybe 4 times.

[randallino]

maybe it's the bumping some people do? I handle mine like fine china just out of habit. I plan to test to satisfy my curiosity but I will be shocked if it's not still accurate.
I agree.
I've got a Sybon and as long as I'm gentle handling the refractometer its fine. I do check calibration about ~3 months.

[SeaHorse_Fanatic]

My Sybon has also remained very accurate. The Vertex refractometers, on the other hand, seem to be a lot more finicky.

[jhj0112]

I also have Sybon and I handle it with really good care.. I am still going to check though...

[mike31154]

I like to think I'm relatively careful with mine, with regard to the bumping & handling biness. It still goes off cal a point or 2 from time to time but I don't sweat it that much. I generally use it when doing water changes to compare the tank water to the new water simply to confirm that the difference is not too much. Water changes are large in my case, about every 21 days so I'm not too keen on shocking the livestock by dumping a bunch of new water with significantly different salinity on them. So, regardless of whether the reading is off (I shoot for 1.025), provided the tank & new water are within 1 point, I go for it.

IMO, it's easy to over think these things. I mean once you have your tank salinity set to the desired value & your top off system is working properly, there really isn't anything other than a water change that will tend to change it. This is why I simply ensure the new water is close to the tank water before I do a change. If I feel ambitious, I'll put a drop of tap water on the refractometer & tweak the adjustment to make it read 0. Other than that, I see the tank virtually every day, so if something's amiss, I investigate. Usually it's not incorrect salinity. After years of running the tank & making up new water in the same container using the same salt, I have a pretty good handle on how many cups I need to mix to get close to 1.025. So should be no reason for the tank salinity to drift more than a point after a water change.

A few years ago I used the refractometer to compare tank water readings with 3 cheap swing arm hydrometers and a floating hydrometer. Salinity showed 1.025 on the refracto. The floater was bang on same as refracto, the swing arm jobs were all off by quite a few points. Rather than turf them in the trash, I put a mark on each of the cheapo swing arm hydrometers to show where 1.025 was according to the refracto. So theoretically I should be able to use the swing arms to confirm whether the refracto has drifted or not. Haven't done that in some time though, so I should probably trash them. Nevertheless, if anyone has a swing arm still kicking around & is concerned about their refracto drifting, they could do the same & use it as a backup. Better yet, invest in a floating hydrometer, they are very accurate, provided you use them at the design temperature, or compensate with a chart.

[wreck]

went out and bought some solution to check mine after reading this thread hadn't tested it in a year or better. it was dead nutz, vertex refractometer. i use it put it back in the case, never gets bumped.