Reef Discussion
It's probably accurate enough. Remember that stability is more important than pinpoint accuracy. Though you should test it with a calbration fluid the same as the level you are aiming for, not RO.
Me, I'm lucky enough to live in Sth Gippsland within travelling distance of several ocean beaches. If I know I'm heading to those beaches I take the refractometer and check it against that. I figure if it's close enough for the ocean who am I to argue. I wouldn't do it anywhere near a built up or disturbed area though.
A good thing the hydrometer is gone though, they're worse than useless.
Me, I'm lucky enough to live in Sth Gippsland within travelling distance of several ocean beaches. If I know I'm heading to those beaches I take the refractometer and check it against that. I figure if it's close enough for the ocean who am I to argue. I wouldn't do it anywhere near a built up or disturbed area though.
A good thing the hydrometer is gone though, they're worse than useless.
I have a red sea refractometer that needs calibration every time you use it so i have a bottle of Accurasea by two little fish to calibrate it with that is 35ppt. Its just expensive sea water though so @IJG3145 has the better idea. A water bottle filled with sea water from a clean beach will last you forever.
Jaycar or Ebay will sell calibration fluids.
find a solution as close to natural salt water as you can (53ms), then use a conversion chart off google to get a specific gravity based on the solution you brought.
Accurasea is a great product off the shelf at many LFS. it is just purified natural salt water, but if you treat it like a check for a million dollars it should last a few years. and is 1.026
RO, even RODI wont give you accuracy. think of the speedo in your car, most are spot on at 60km, but out by a little at 110km. best to calibrate to a number close to what it will be testing.
Melbourne sea water can vary a little in the bay, but is generally 1.028 on a high tide at Mornington.
another simple way that will be find-able on google somewhere as my head hurts from a long day, so math is out of the question.
using artificial salt water, X grams per liter = (specific gravity). randy made his own versions too.
like ALL parameters STABILITY is number 1!
Tip. although most refractometers are ATC, auto temp compensating. float your test solution in the tank for 5 minutes. that way you will calibrate the refractometer at the same temp as the water that will be tested.
find a solution as close to natural salt water as you can (53ms), then use a conversion chart off google to get a specific gravity based on the solution you brought.
Accurasea is a great product off the shelf at many LFS. it is just purified natural salt water, but if you treat it like a check for a million dollars it should last a few years. and is 1.026
RO, even RODI wont give you accuracy. think of the speedo in your car, most are spot on at 60km, but out by a little at 110km. best to calibrate to a number close to what it will be testing.
Melbourne sea water can vary a little in the bay, but is generally 1.028 on a high tide at Mornington.
another simple way that will be find-able on google somewhere as my head hurts from a long day, so math is out of the question.
using artificial salt water, X grams per liter = (specific gravity). randy made his own versions too.
like ALL parameters STABILITY is number 1!
Tip. although most refractometers are ATC, auto temp compensating. float your test solution in the tank for 5 minutes. that way you will calibrate the refractometer at the same temp as the water that will be tested.
Similar to what everyone above has written, I use the NSW I collect as the reference and monitor how my tanks water varies from that.
My refractometer tells me the NSW I collect is at 1.029.
My tank stays at 1.029-1.030 and is normally very stable.
At this stage I don't really care what the actual salinity level is as long as it is stable and as long as it doesn't vary much from 1.029 as that is what the NSW is I'm adding.
Not sure where your salt water comes from, but if your refractometer isn't stable and your mixing your own salt water then yeah, you should get a calibration liquid, but if your refractometer is stable and you are getting the same saltwater, as IGJ345 does (like me) just use it as a reference.
My refractometer tells me the NSW I collect is at 1.029.
My tank stays at 1.029-1.030 and is normally very stable.
At this stage I don't really care what the actual salinity level is as long as it is stable and as long as it doesn't vary much from 1.029 as that is what the NSW is I'm adding.
Not sure where your salt water comes from, but if your refractometer isn't stable and your mixing your own salt water then yeah, you should get a calibration liquid, but if your refractometer is stable and you are getting the same saltwater, as IGJ345 does (like me) just use it as a reference.
I'm an old fart and it took me many years to learn how to take a step back and look for anything obvious I was missing. I was literally collecting NSW and looking at the ocean when I suddenly thought "why am I using a little bottle from an industrial chemist* to compare my tank against this". It occurred to me to test my tank against the real 'this'. :)
Similarly I was for no reason, reading the label on home brand plain green scourers, I realised they were inert and had way more surface area than the expensive jap matting I was using. I now use scourers to house bacteria for transfer to QT tanks, etc.
*just where I get/got mine - my old boss.
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