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markush
05/14/2005, 02:50 AM
Hi, I wanted to pose my questions to you here because after reading your article on Hydrometer Corrections i figured you would give me a straight forward answer and not the "just get a refractormeter" answer so prevalent in these forums.

Wanting to update my 7 year old Aquarium Systems swing arm hydrometer i purchased a Marine Enterprises glass hydrometer. On my way home i stop at a LFS that uses a Tropic Marin hydrometer to compare it with mine. They tell me mine reads 1.0212 while the Tropic Marin reads 1.0226. Taking into account that mine is calibrated to 75 degrees F and the Tropic Marin 77, to put them on even ground i give mine a temperature correction of plus .0007 for a reading of 1.0219. So basically mine is reading .0007 lower then the Tropic Marin.

The problem is when i get home and float mine in 75 degree DI water it reads 1.0022, .0022 higher then it should!? I know i'm making a mountain out of a mole hill but would you suggest i just use the Tropic Marin as a reference for my readings and always add the .0007 or use the DI numbers and subtract .0022?

ScubaRaven
05/14/2005, 09:54 PM
I once purchased 4 different brand name swing arm hydrometers and they all read different!!! Seriously... I ended up buying a refractometer. I still use my swingarm but atleast I have something to correctly calibrate it against.

Rich Valentine

Randy Holmes-Farley
06/08/2005, 10:43 AM
Sorry, I don't check this forum that often. I can always be reached quickly in the RC chemistry forum, where we replied:

http://reefcentral.com/forums/showthread.php?s=&threadid=592510