The Puffer Forum

I just bought an Instant Ocean hydrometer. Before checking the SG in my mudskipper tank, I checked that of my freshwater one first. It reads 1.002, is this normal.

did you wash it thouroughly first? was it used? also knocking the air bubbles off the swing arm and setting it on a level surface will all help get the best measure

Brand new, washed it out, tapped it for bubbles...

Yup, they're not always 100% on target. You could either add .002 to every measurement you get (I believe that is how it works) or return it for one that you check out against a refractometer (that would be best).

Are refractometers much more expensive?.. I can only imagine they are... I also checked my tap water and it was also at around 1.002

kass wrote:Are refractometers much more expensive?.. I can only imagine they are...

$40.79 at drsfostersmith.com. You might be able to find them a few bucks cheaper on EBay.

It is best to invest in a good hydrometer, especially if you ever decide to go salt, that little difference I have learned can make a huge deal.

I found that temperature of the water makes a difference too, when I tested my tap water cold it was quite different to that of my freshwater tank water ( about 0.002 I think but it was awhile ago so I may be mistaken) maybe that's the difference? have you tried warming the water and then testing it again?
Sue

Hydrometers measure the density of the liquid they are in. The density is affected by the temperature. It is important to note what the temperature the hydrometer was calibrated at. There are sites online and tables that you can use to get an accurate reading depending on the temperature of the water you are testing.

Ted

There is a refractometer for $39.99 from: http://www.marinedepot.com/md_viewItem. ... roduct=_A6 I have ordered it and am waiting for it to arrive.