Hydrometers

[Betta5]

In my LFS they only sell glass ones. I have herd they are not as good as the swing arm ones. Can i get the glass one?

thanks

 

[steelhealr]

Get a refactometer. SH

 

[Betta5]

I dont want a reef or anything, just FO or FOWLR

 

[Mr.September15]

It doesnt really matter what you want when it comes to measuring for salinity or S.G. It's pretty much about accuracy, refractometers are an easy way to measure salinity/S.G because all you need is to calaborate it and pour a few drops of SW on the little thingy. But it comes with a hefty price which is why most marine keepers go with the swing arm. I've never used the glass one, are you talking about the ones that float in the water and are used as a thermometer too?

 

[AliRichardson]

Ive never heard of a refractometer, but then I havent been doing this for long...

Someone please tell me more about them! I have studied chemistry at degree level so if it needs a sciency explanation i wont shy away

 

[andywg]

A refractometer measures the salinity of water by virtue of the fact that light refracts at a different rate through salt water than pure water. The more salt in the water, the more it refracts. It has one large advantage over hydrometers (which work by effectively "weighing" the water) in that it is not temperature sensitive.

Refractometers are used for a number of different simple chemical analyses looking for the presence of different elements and compounds in liquid.

Swing arm hydros are considered the cheapest and least accurate. All it takes is a small bubble in the works and it will give an off reading. The floating ones are better, though even these tend to be out quite a bit.

A decent refractometer will need the occasional calibration with pure (RO or DI) water and will then work and be accurate at all temperatures we would be testing them on.

 

[tmreynolds]

Refractometers don't need to be that expensive, mine was ~£20 off eBay. I used to use a hydrometer, but refractometers are much more accurate

 

[steelhealr]

....and they're fun to use....good explanation andywg. SH