Refractometer

Right, the "blue" RHS-10ATC" - measured "perfect" right out of box...

S

 

Right, the "blue" RHS-10ATC" - measured "perfect" right out of box...

How can it do that ? We are assuming again, correct. It is calibrated with a 3.5 % NaCl (35 ppt, 1.0264 SG), which means it will always read 1 ppt to low or 1 SG to low. What did you measure it against to be perfect ? For it to measure perfect, you must make up a 3.6 % solution of NaCl and then recalibrate it so the lines meet at 3.5 % (35 ppt) with that 3.6 % solution @ 25 C on the plate. Only then is it perfect. Then it wil be set to seawater. Seawater has a higher Refraction Index (RI) than NaCl.

Omard, try calling or going to the local drug stroe, where the chemist can make up the solution for you . Then you counld really post some info out on swing-arms or floaters, as the refract would be right on the nuts, no room for arguments

 

Sorry Boomer, guess I mispoke - :-[

What I "meant" to say...is mine matched the exact reading as the one used by the "Master Water Guru" at the Seattle Aquarium...right out of box...

May not be "on the nuts" - but close enough for me...

THX for correction.

OmarD

 

Boomer,
What Scott did was take a water sample from his tank to the Aquarium and they tested the water with the type they use and they ended up with the exact same reading.

 

Sorry Boomer, guess I mispoke -

Maybe I did Guess I missed that in the thread >

Just for the sake of argument, I also question the aquarium water guru, did he or does he know that refracts are off out of the box by .001 or .1 %, 1 ppt. Few people actually know this, it is something Randy and I have been passing along in recent months and is the reason Randy made up a std for refracts. If our goal is to have the tank the same or near the same, as NSW, that refract should read 3.6 %, 36 ppt or 1.0274 SG = NSW @ , 3.5 %, 35 ppt or 1.0264.

The issue has been people comparing devices to measure SG or salinity and many times assuming that device x is better than device y. Ex. one takes a refract and compares it to some type of hydrometer and assumes for some reason, that because it is a refract, it MUST be correct and the hydrometer must WRONG and that is not the case. You need to use a std to see which is correct.

What is nice about refracts, as I posted before, is that there is less chance for most reefers to make an error. Usually that error is only the refract being 1 unit to low out of the box and the reason behind the 1 unit add on. Even without the add on the refract is usually only 1 unit to low, i.e. 34 ppt instead of the expected 35 ppt, which we could say "close enough". And a reef tank at 34 ppt is not a real issue to argue over.

However, when one takes up the issue of comparing on device to another then it is a different beast, all the variables must be looked at i.e, temp error, calibration temp,out of the box error etc.. This is the reason such units should be measured against a std, as only then do you really know what is what.

Lets look at it in another way. You have a Nitrate test kit, brand x and it measures 5 ppm and a friend has another nitrate test kit y, one of the Cadillac kits and it measures 22 ppm. You will automatically assume that yours is junk, when in fact it may be right on the noise. Reason, you did not know that one kit (yours) measures nitrate as NO3-N and the other measures it as NO3 and

1 ppm NO3-N = 4.4 ppm NO3

So, your 5 ppm NO3-N x 4.4 = 22 ppm NO3, the same exact level.