Does heat affect specific gravity?

[nahla]

Will specific gravity change with the temperature of the tank?

 

[HoopsGuru]

Yes, and most of the plastic swing arm hydrometers are calibrated to a certain degree (most often 77° or so) so this must be taken into some consideration as well.

 

[smooth_rivers]

In which direction Hoops? Higher temp = higher SG?

 

[reefrunner69]

http://www.algone.com/salinity.htm

 

[smooth_rivers]

holy **** batman...
thx

 

[toddwess]

Okay first of all - thanks for the link to the chart!

Second of all - If I keep my tank at 80 degrees (which I do) and I would like my water to be at 1.024 (which I do) then I should shoot for a reading of 1.022 on my plastic hydrometer -- right?


Todd

 

[Dewey]

wow--------- thats neat i never knew they were calberated at those temps.


Thanks Dewey

 

[HoopsGuru]

Second of all - If I keep my tank at 80 degrees (which I do) and I would like my water to be at 1.024 (which I do) then I should shoot for a reading of 1.022 on my plastic hydrometer -- right?

Depends Todd, any idea what your plastic hydrometer is calibrated to? I shouldn't have said "most" in my previous thread...the Deep Sixx I know is calibrated to 77° (at least when I bought it).

IMO, for most hobbyists being in the general range of appropriate s.g. is good enough and it is more important to be stable than anything else (within reason).

 

[leafyseadragon]

Thanks for the link, reefrunner.

I noticed that the article states the hydrometer is calibrated for a temperature of 60˚F (15.55˚C). But I have a SeaTest hydrometer, and it says that it's "designed for use in warm water aquariums (68˚-85˚F)." So it seems to me that since this hydrometer is not calibrated to 60 degrees, the table in the article only sort of applies.

Any idea on what the corrections are for the SeaTest hydrometer?

 

[toddwess]

Hmm, not sure. However, I too have the Coralife Deep Six Hydrometer so they are probably along the same calibration, I would guess.

We could always fork over $160 for one of those hold-up-to-the-light-and-look-through salinity meters!

Thanks,
Todd

 

[reefrunner69]

We could always fork over $160 for one of those hold-up-to-the-light-and-look-through salinity meters

I have one of those I paid 43.00 for it, before shipping.

Try this article by Randy, it might confuse you more, but then again it might help. He specifically addesses the issue of temperature correction with swing arm hydrometers.

 

[reefrunner69]

This is pretty cool too

http://www.wymag.org.uk/simon/salinityhr.htm

Try this article by Randy

it would help if I provided the link...

http://www.advancedaquarist.com/issues/jan2002/chemistry.htm