Dropping Salinity?

[johnnyjtaylor]

My salinity seems to have dropped from 1.025 to 1.023. My tanks only been running for 2 weeks, is this something that can happen or is the hydrometer I bought a bit poo??? It is one of those swing arm types but I do rinse it thoroughly in clean water after every use.
Cheers Johnny

 

[callell]

My suggestion would be - to get a Refractometer (far more accurate)

Swing arms are a nightmare imo

 

[johnnyjtaylor]

My suggestion would be - to get a Refractometer (far more accurate)

Swing arms are a nightmare imo

O.k cheers ,but my more imediate concern is can the salinity fluctuate??(I'm guessing no but I don't have experiance with SW so I can't be sure)

 

[Mr Miagi]

Not without a source of freshwater input. As water evaporates, it leaves salt behind, so excessive evaporation should only cause an increase in salinity. If your testing Salinity, it should be uniform over temperature. S.G. is affected by temperature however. My guess is its your swing arm. They can vary GREATLY.

 

[johnnyjtaylor]

Thanks Mr Miagi,
thats kinda what I thought(but lack of knowledge made me unsure). Better order myself a better quality instrument(refractometer). The tw*tt in the LFS said "these are the best hydrometers, only £15" I should have known when it was made out of plastic!

 

[Mr Miagi]

Well considering their reputation, I imagine a .002 swing isn't un-heard of. Best to get something more accurate if you can. That LFS guy does sound like a bit of a nugget.