Refractometers

[thincat]

I want to know how you all care for your Refractometer.
Cleaning:
calibration:
and overall care.....

 

[CaptainAhab]

Wipe it off, put it back in the case.

Calibration: Probably not nearly enough.. maybe once ever other month or so (more on the 'or so' side)

 

[Kurt_Nelson]

Same as the capt'n. But probably even spottier on the calibration - it's never needed adjustment.

 

[neilanh]

I check mine every 4-8 weeks, whenever I think about it. I've not yet had to recalibrate it. Also I just use RO/DI water for the calibration.

As for cleaning, yeah, wipe it or rinse the SW off of it, that's about it.

 

[roka64]

Same here, just wipe off with a damp cloth, to get the SW off then use a dry cloth to get the moisture off. I have yet to re-calibrate mine....oooppppssssss.......

 

[Zer0]

Yeah, same here. I would suggest that once you read the salinity, you get rid of the saltwater as quick as possible. You know the devil that saltwater drops turn in to when they dry off. Even if it looks like you got all of the water out, there still may be some leftover in the extremely tiny edges where the metal and the glass panel meet. So, just like the rest said, the damp cloth will get rid of anything like that.

As for calibrating it, if you don't have the calibration fluid (which personally i think is a complete waste of money and a scam.), you can just use RO water. First put two drops of water on the glass panel, then hold the eyepiece up to a light source and read what it says. When i was going to calibrate my refract, the whole eyepiece read white, which means it wasnt calibrated. Depending on what kind of refract you get, there will be a little screw in a hole in the refract's body. That's the screw that is used to calibrate the refract. Most of the time, when you buy the refract, it will come with a little screwdriver designed small enough to get to the screw. All you need to do, is turn the screw clockwise. If your looking in the eyepeice, you will see a blue slide going upwards toward the numbers. You want that blue slide to exactly touch zero. Once you get the blue side matched with the line on zero, it's calibrated. Hope this wasn't too confusing.. :s sorry. I remember explaining this to someone else, but i forgot what i said then. xD

So.. just incase my explination before was idiotically unclear, here's the quote from JOM20's build thread that helped 3 people!!

All you've got to do to calibrate it, is only put a drop of water on the glass part, then close the sunlid and make sure it spreads all the water out on the lens. Then use the screwdriver it came with, and see that little black dot on the top? That rubber piece comes off and there's a small hole in there. After you put the screw driver in there, look into the eye piece and turn the screwdriver until the white line is exactly at 0. Wa-la you've calibrated it. But like roka said, either do this with ro/di water or with calibration fluid. I practiced calibrating mine with regular water, so thats why i know how to do it.

 

[melosu58]

I`m about the same as everyone else.

 

[ccCapt]

As for calibrating it, if you don't have the calibration fluid (which personally i think is a complete waste of money and a scam.), you can just use RO water.

Yes, while you can use RO water to calibrate it, it will be calibrated for SALTWATER, not SEAWATER. If you calibrate with RO, to get a true reading of 35 ppt for SEAWATER, your refracto should read 36.7 ppt.
If you calibrate with calibration fluid, SEAWATER will read a true 35 ppt.

I calibrate with calibration fluid for every water change. It takes all of 30 secs to do.

Refractometers and Salinity Measurement
"Refractometers can lead to incorrect readings in additional ways and, again, these issues abound for reef aquarists. One is that many refractometers are intended to measure sodium chloride solutions, not seawater. These are often called salt or brine refractometers. Despite the scale reading in ppt (‰) or specific gravity, they are not intended to be used for seawater. Unfortunately, many refractometers used by aquarists fall into this category. In fact, very few refractometers used by hobbyists are true seawater refractometers.
Fortunately for aquarists, the differences between a salt refractometer and a seawater refractometer are not too large. A 35 ppt sodium chloride solution (3.5 weight percent sodium chloride in water) has the same refractive index as a 33.3 ppt seawater solution, so the error in using a perfectly calibrated salt refractometer is about 1.7 ppt, or 5% of the total salinity. This error is significant, in my opinion, but not usually enough to cause a reef aquarium to fail, assuming the aquarist has targeted an appropriate salinity in the first place."

 

[Zer0]

Heh, never knew any of this. Someone told me it could be calibrated the same using RO water, so that was my take on it. Thanks for that info ccCapt.

 

[CaptainAhab]

most, if not all, of the manufacturers instructions say to use RO/distilled water too. I remember ccC posting it before. I can just never find it (the posting)

 

[ccCapt]

Yes, that's true, because they are made to measure saline solutions (brine/saltwater) and using RO water will properly calibrate it for a saline solution. We use seawater in our tanks...it's a different beast.

 

[Zer0]

Well then, would my salinity be incorrect right now? And would it be off by one point? And if so.. then everytime i measure the salinity, should i subtract or add that extra point that you stated before? Or am i getting in to a whole new ballgame with those questions..

 

[HappyHooligan]

I quit with refract. and hydrometers.
I just dip my finger in the tank and taste it

 

[ccCapt]

Well then, would my salinity be incorrect right now? And would it be off by one point? And if so.. then everytime i measure the salinity, should i subtract or add that extra point that you stated before? Or am i getting in to a whole new ballgame with those questions..

If you calibrated with RO, you are off by aprox 5%. If you want to be at 35 ppt and you calibrate with RO, your refracto should read ~37 ppt. If you are showing 35 ppt, you are actually at ~33.3.

From the article I linked to...
A 35 ppt sodium chloride solution (3.5 weight percent sodium chloride in water) has the same refractive index as a 33.3 ppt seawater solution, so the error in using a perfectly calibrated salt refractometer is about 1.7 ppt, or 5% of the total salinity.

 

[Zer0]

Alrighty then. Thanks for that clear up. Guess i will have to take that in to consideration from now on whenever testing the tank and my PWC water..

 

[thincat]

I use RO to calibrate my refracto. I rinse with RO water then wipe dry. If you use the same refracto and get the same reading everytime you mix your salt...IMO that is close enough. It's a drastic change in SG that will kill your fish and corals. That and temp variations.

 

[ryshark]

If you calibrated with RO, you are off by aprox 5%. If you want to be at 35 ppt and you calibrate with RO, your refracto should read ~37 ppt. If you are showing 35 ppt, you are actually at ~33.3.

From the article I linked to...
A 35 ppt sodium chloride solution (3.5 weight percent sodium chloride in water) has the same refractive index as a 33.3 ppt seawater solution, so the error in using a perfectly calibrated salt refractometer is about 1.7 ppt, or 5% of the total salinity.

Good info from Cccapt here. until a couple weeks ago I only calibrated with RO/DI water. When I purchased the calibration solution it showed that the RO/DI was off. I thought I was at 1.025 but I was really at 1.022! I think my sps coral will appreciate 1.025 much more than the low salinity I had them in. I am now in the process of raising it up to a "more accurate" 1.025.

 

[Aquarium1]

What is more important? SG or salinity? What would be an optimal salinity level?

 

[ryshark]

What is more important? SG or salinity? What would be an optimal salinity level?

Basically they are different ways of measuring the same thing. I like salinity around 35ppt which is a SG of around 1.026
As far as what is optimal, it depends on what you have in your tank and that will help determine what is optimal for you.

 

[Zer0]

+1 ryshark.

Most sites that i have visited that sell livestock, say anywhere from 1.022-1.025. And that's a pretty good boundary for livestock.