Red Sea Refractometer driving me crazy
- Thread starter thelawnwrangler
- Start date
I've bought generic refracs and never EVER had to calibrate one before it outright lost the plate-pin from rust or otherwise wore out.
Suggest you be very careful to clear the collection tube each time and pump it a few times to be SURE you get only your current water in. Leaving salt water in that tube, where it can dry out and then re-wet as you intake water can really skew the next reading. Likewise and for the same reason be sure to dry the plate at each use, so there's no residual salt left on the blue plate.
Suggest you be very careful to clear the collection tube each time and pump it a few times to be SURE you get only your current water in. Leaving salt water in that tube, where it can dry out and then re-wet as you intake water can really skew the next reading. Likewise and for the same reason be sure to dry the plate at each use, so there's no residual salt left on the blue plate.
AboutAcans
New member
I hate refractometers in general. Can't stand them. Been keeping reefs for 25+ years, over 27000 galloms. I'm still at Deep Size Hydrometers and flicking off bubbles. And I even have Apex units. Hydrometers are the closest for to actual physics IMO
jason2459
Well-known member
Conductivity would be the method of choice for that and standard method for scientists now a days.
AboutAcans
New member
No where even close to accurate. Consensus will always be the simplest forms of physics. And a needle floating to show actual salinity will always be there most basic form of physics. And also it would be be biologists. "Scientists" is an erroneous definition on it's own.:bounce3:
JZinCO
New member
salinity is a physical measurement. It is not the domain of biologists. Biologists and other practitioners of science use salinity. If it of more concern to some branch more than others, the precise measurement of salinity is of most concern to applied physicists and engineers who specialize in understanding material properties and the agencies they work for, such as NIST. And the direct way to measure salinity is through simultaneous measurement of chlorinity (conductance), temperature and pressure. We ignore temperature and pressure in readings because the instruments readouts assume a given temperature and pressure (1 atm generally). Neither refractometers nor hydrometers actually read salinity, they read the properties of saline solutions: either the effect of salinity on bouyancy or light refraction.
- a 'scientist'
edit: sorry, off topic to original post.
- a 'scientist'
edit: sorry, off topic to original post.
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heathlindner25
New member
Love it :hmm5:
whosurcaddie
New member
I got a cheap $20.00 version on Amazon I've only calibrated it once. Its held true the entire time I've had it.
jason2459
Well-known member
I would refer you to An Introduction to the Chemistry of the Sea by Pilson. Excellent book.
AboutAcans
New member
"Neither refractometers nor hydrometers actually read salinity," Pretty sure 99% of the board went WTH!!! After this part. No, they register salinity. The buoyancy of water based on the biological factors which contribute to it's specific gravity.
Completely missed my point. It's called Occam's Razor. It means the simplest and easiest answer is usually the correct one. And a hydrometer is the simplest method of measuring a compound, in this case sea water salinity; which means operated properly, it will always be the most accurate. Someone is trying to explain the physics and engineering that went into something, how it was built, or whatever they're trying to say, which is why it makes it more accurate. Just means there's more components that the actual physical reading has to go through before it can even give it's reading. Just means more things to screw up the reading. Occam's Razor - a hydrometer will always have a larger chance of being most accurate due to it's simplicity.
I remember 10 years ago when the board was arguing over the best way to "season" a hydrometer for the most accurate reading HAHA
Anyways, I can do this now. Then I'm off this post and won't read another thing added to it. It's the benefit of never doubting myself. That and this thread had about 5 trolls jump on it in the last 45 minutes.
THREAD OWNED!!!!
Completely missed my point. It's called Occam's Razor. It means the simplest and easiest answer is usually the correct one. And a hydrometer is the simplest method of measuring a compound, in this case sea water salinity; which means operated properly, it will always be the most accurate. Someone is trying to explain the physics and engineering that went into something, how it was built, or whatever they're trying to say, which is why it makes it more accurate. Just means there's more components that the actual physical reading has to go through before it can even give it's reading. Just means more things to screw up the reading. Occam's Razor - a hydrometer will always have a larger chance of being most accurate due to it's simplicity.
I remember 10 years ago when the board was arguing over the best way to "season" a hydrometer for the most accurate reading HAHA
Anyways, I can do this now. Then I'm off this post and won't read another thing added to it. It's the benefit of never doubting myself. That and this thread had about 5 trolls jump on it in the last 45 minutes.
THREAD OWNED!!!!
JZinCO
New member
Great point. In that case you should use titration to measure the g of salts per kg of water since that is the simplest. it directly measures salinity and does not invoke any properties of saline solutions. Or if you got the idea from my post, you can accept there are multiple measurable properties of salinity. The relationships of refraction and buoyancy as a function of temperature, chlorinity and pressure are well known. What you choose is just fine as long as the measurement uncertainty (e.g. observer and instrument) meets your desired accuracy. No reason to sh*t on others for using different instruments. I've noticed from your posts that you tend to be very critical of others who do things in ways other than yours.
As a side note. there are no "biological" factors involved in salinity. A swing arm hydrometers moves because of the work the fluid does on the swing arm owing to its density, which is called bouyancy. This is a fluid dynamics 101 problem.
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jason2459
Well-known member
This thread has just gotten worse. For anyone interested in the study of seawater and chemistry of your tank. I highly suggest that book I just referred to. It's also available on Kindle and is written so most anyone can understand.
Otherwise, go to the Chemistry subforum stickies and there's many great free articles you can read.
Otherwise, go to the Chemistry subforum stickies and there's many great free articles you can read.
JZinCO
New member
Methods of seawater analysis is good too but written more for wet lab chemists.i t has a chapter on measuring salinity. Still any reefer that is Uber interested in this topic will find good content in there.
jason2459
Well-known member
Nice. By chance have you looked at JimWelsh's thread on Salinity determination by density? Its not on this forum so I won't post a direct link but a google search with " Salinity determination by density JimWelsh" will return the desired results. Which is the title of the thread and Author.
CStrickland
New member
Is it appropriate to call it salinity, or is something like density closer to what we measure? I wonder because I have heard of situations (I believe using balling method, and extreme no water change tanks) where the specific gravity will remain the same, but the salinity drifts. This isn't an issue for most of us and wouldn't be a reason to buy one measuring tool over another, just curious since the rest of the thread is pretty technical.
Also, by Acan's logic we would be better off talking to each other through tin cans connected by string than telephones, because it is a simpler contraption. Lol. Their explanation of Occam's razor left out the part where the competing theories are equally functional. Here, the factors that make a tool better: accuracy, reliability, price, ease of use etc need to be accounted for first. obvi.
My swing arm worked fine until I broke it. For a few dollars more the generic atc seemed like a good investment.
Also, by Acan's logic we would be better off talking to each other through tin cans connected by string than telephones, because it is a simpler contraption. Lol. Their explanation of Occam's razor left out the part where the competing theories are equally functional. Here, the factors that make a tool better: accuracy, reliability, price, ease of use etc need to be accounted for first. obvi.
My swing arm worked fine until I broke it. For a few dollars more the generic atc seemed like a good investment.
jason2459
Well-known member
Swing arm hydrometers can work fine as long as they are used right.
The salinity of the surface levels of the ocean has an average close to 35PSU (practical salinity units). But that's just an average. It varies from location to location and some locations can have daily and seasonal shifts.
So, personally I wouldn't get worked up about exact accuracy but more about consistency or precision.
Which comes back to the OP. The Redsea refractometer is not precise which IMO is more important then accuracy for this measurement.
On the topic of what is density and specific gravity this is a detailed breakdown. Note in the link water is listed at 4Celcius. That is when it is at its most dense. Water is a very unique substance.
http://www.engineeringtoolbox.com/density-specific-weight-gravity-d_290.html
The salinity of the surface levels of the ocean has an average close to 35PSU (practical salinity units). But that's just an average. It varies from location to location and some locations can have daily and seasonal shifts.
So, personally I wouldn't get worked up about exact accuracy but more about consistency or precision.
Which comes back to the OP. The Redsea refractometer is not precise which IMO is more important then accuracy for this measurement.
On the topic of what is density and specific gravity this is a detailed breakdown. Note in the link water is listed at 4Celcius. That is when it is at its most dense. Water is a very unique substance.
http://www.engineeringtoolbox.com/density-specific-weight-gravity-d_290.html
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