Jump to content

How off is your hydrometer!


zerocool5878

Recommended Posts

zerocool5878

I have been maintaining

my nano reef at 1.023sg

75 gal FO 1.019

And my sons pico fowlr at 1.019

all with a hydrometer. I have 2 of them and they always give the same reults. One of them is only 1 month old. I always rinse them after testing and boy are they off.

 

Today i bought a refractometer at my LFS. They were showing me how off these really are right in the store. They calibrated it and showed me how it works. I came home and tested all 3 of my tanks.

 

nano 1.026

75 FO 1.021

pico fowlR 1.021

 

Im really glad I bought this.

 

Cheers

Link to comment

I know my FOWLR is sitting at 1.024 and i maintain that with my hydrometer that consistently reads 1.018. it works well enough even if i cant shoot for a diff SG.

Link to comment

mine reads 1.022 so i added more salt came out to 1.023ish, had a guy measure it with refractometer ? or was it chemical, he said it was a bit high, 1.026 so he said my meter was off by 4...

 

oh ya mine is the deep 6 by coralife

 

oh ya again, i heard you should measure at 80*F?..

Link to comment
zerocool5878
IIRC you have to use the hydrometer at the correct temperature.

:)

 

 

I believe that to be incorrect. the two that I have are Seatest and instant ocean swing arm hyrometers. These are no supposed to require temp correction.

 

However they do suck at measuring sg.

 

I don't think that the standard corrections would apply to these 2 hydrometers.

Link to comment

.002

Although temp DOES matter, due to thermal expansion, which affects density (Specific Gravity) but the effect is so miniscule, it doesn't matter for our purposes.

Volume after Expansion= (Coefficient of expansion)(Volume original)( Delta T)

So if you have a given volume of say, 100, and the hydrometer is meant to read at 75 and your tank is 81, then the percent error is... .126%... so the hydrometer would read roughly 1.026 instead of 1.025. But Hydrometers are so inaccurate due to other reasons (miss manufacturing, bubbles, etc) temp differences are negligable.

Link to comment

Archived

This topic is now archived and is closed to further replies.

  • Recommended Discussions

×
×
  • Create New...