Salinity meters/hydrometers

[Carmen]

Refractometer - THE ONLY way to go! Well worth the investment and you may be able to find one used for half the price!

[parkinsn]

Refractometer hands down!! You can get them fairly inexpensive if you look around.... like $40. $40 to keep hundreds or thousands of $$$ in live stock alive is worth it to me.

[Glennrf38]

BCOrchidGuy....... I am a cheap SOB But I think my refractometer was well worth the cost. My hydrometer was showing 1.023 and my refractometer showed it was really 1.031. Wow......

[BCOrchidGuy]

Well, considering the cost of the IO one I have, the Coralife one and the Red Sea, plus the glass one I could have bought a refractometer. I guess that's next on the shopping list.

Thanks for the replies folks

[Snaz]

Certainly refractometers are easiest and fastest but a clean, calibrated and appropriate hydrometer is more accruate. To be clear I mean a long glass cylinder hydrometer, not the plastic swing arm type found in Capt. Crunch cereal boxes.

Are you reading the glass hydrometer correctly? Make sure you are reading at the lowest level of the Meniscus.
http://en.wikipedia.org/wiki/Meniscus

What model of hydromter are you using? It will be somewhere on the paper within.

[BCOrchidGuy]

Yes reading from the bottom of the meniscus, I think it is a coralife but the paper insert must have moved because it was floating higher than it should have been. Not a big deal I know you need to compensate on them but the plastic ones are all over the place with the readings. Oh and one air bubble can screw up the arm on the plastic ones as well, make it read wayyyy higher.

Douglas

[Snaz]

Originally Posted by BCOrchidGuy

I think it is a coralife but the paper insert must have moved because it was floating higher than it should have been.

If you suspect the paper has moved in any hydrometer, chuck it out. Useless.

Any good glass hydrometer will have a green or red mark on the inside of the glass that matches same mark on the paper. If they don't line up then the paper has moved. Chuck it.

[BCOrchidGuy]

Chucked !!! with extreme prejudice

[mark]

Have a Refractometer myself but do laugh a bit as we (myself included) go on how they're so much better than a swing arm hydrometer.

Been ages since verified mine against ro water and never have actually made a test solution for the range in which I use mine. Really without frequent verification there are no better than a swing arm type.

[mike31154]

With swingarm & glass hydrometers people often don't realize or forget that these are calibrated at a set temperature and if the water you are measuring is significantly off that temperature, it will affect the reading. Most of the newer refractometers have automatic temperature compensation so provided you wait a few moments for the liquid to reach temperature parity with the refracto, you're good to go.

I just measured my tank water with 4 different components:;

Glass Hydro with thermometer: 1.024+ @ 74 Fahrenheit (there's a mark at 78 F so I assume that's the manufacturer's calibration temperature)
Refractometer: 1.024+ (auto temp compensation)
Instant Ocean swing arm: 1.0234 @ ? Fahrenheit, presumably same as glass hydro
Coralife Deep Six swing arm: 1.0216 @ ? Fahrenheit - same story as IO swing arm

Note the extra decimal place for the cheapo swing arm jobbies. That's because the scale on both of these is fairly large making it easier to read off to that level of accuracy. Both the glass hydrometer and refracto scales are much tighter and for me this makes it almost impossible to read anything beyond that 3rd decimal. So one could argue that the swing arm hydros offer an advantage in this regard, provided they are accurate to begin with and one has the temperature compensation chart handy.

I kind of like the floating glass hydrometer. It's a tried and true technology. Different versions of these have been used for decades to measure specific gravity of battery acid, anti freeze in your radiator, sugar content for potential alcohol of that home made wine.... Same goes for refractos, one for almost every flavour.