This refractometer any good?

[Dasani]

My dad and I want to get a refractometer. He has the cash and has no clue what he's buying. He said he read somewhere you have to have some kind of blue liquid to calaberate it... is that ture? It's 0-10% ATC with calaberation knob. Is this one any good?

http://cgi.ebay.com/New-Salinity-Refractom...7#ht_3513wt_974

[Clavius85]

You get what you pay for.

[nanoreef-R]

It could be good but I woulnd't trust. Go for something like this

[fireFlies]

The best aquatic fish store in chicago uses a 800$ digital refractometer. Their backup, which they still use is the C-Scope (http://jbjlighting.com/prod-c-scope.html). They said for the price, its the best refractometer. Its the one I use and it works very well. Its almost dead on with their digital expensive one.

 

I would definetly not buy that junk off ebay IMO.

 

You callibrate it with RO water you get from your LFS (not sure how that one works, wouldnt trust it at all). When you use it with RO water it should be 0.00

If its not, you adjust it so it is. You can try it a few times to be sure. The C-scope takes temperature into consideration as most cheap ones dont. There temperature alone can make it off 4-5 points. Trust me, get one that self calibrates for temperature, otherwise its a 22$ piece of junk since whatever it says you know is off (4-5 points just on temperature alone!). Id rather use the hydrometer with arrow instead of that thing...complete waste...even looks like poorly made trash...

[StevieT]

That thing just looks like junk then you look at the price and you know it is junk. I honestly would trust a hydrometer more

[geewiz]

in reality there is not much to a refractometer. but there are two things. first, is does it work??? ok so next is has it been calibrated corectly. if those two things are ok then your good. in fact you are excellent. in fact you could spend $8000 and you wouldnt be any better.

 

so say you have the first thing down, it works, next you have got to calibrate it correctly. using pure water is not the correct way to calibrate a refrctometer. sure it will calibrate the refractometer to pure water but it will not calibrate it to the water you need to test. this is where an $800 unit may preform better... it may allow a more accurate and precise measurement accross a wider range of salintity. cool stuff but,, you need a unit that is accurate and precise in the range you need to mesure.

so back to calibrating, the best way to make sure the meter is accurate and precise in the range you need to measure is to use a standard in your test range or close to your test range !not pure water! randy holmes-farley has an excellent article on using and creating your own standard. search: reef aquarium salinity

 

to quote a selection from his article

 

"It is widely believed that only pure water is required to calibrate refractometers. That fact is true of many refractometers, and is certainly appropriate for routine calibration, but it assumes that they were manufactured correctly and have not been damaged since manufacturing. As refractometers used by aquarists become less and less expensive (with some now selling for less than $30), there is every reason to believe that at some point they will no longer be accurate enough.

 

The only way to be sure that a given refractometer gives useful information is to check its accuracy in a solution similar to aquarium water."

 

so i guess my point is if the meter works buy it then calibrate it. i did and im spot on.