HELP! Measuring specific gravity - newbie question

Afterdark · 05-06-2005, 08:59 AM

I am sure I read this somewhere but cant find it anywhere

My hydrometer measures density in oz/gallon, how can I convert this to a specific gravity type reading. e.g. 1.025?

Thanks

AD

Clownfishman · 05-06-2005, 04:34 PM

Go buy a hydrometer that shows you specific gravity... Instant Ocean makes them lots of companies have them...

I don't know much about the mathematics involved in converting your readings..

PBearslax36 · 06-03-2005, 10:40 PM

Quote:

Originally Posted by Afterdark

I am sure I read this somewhere but cant find it anywhere

My hydrometer measures density in oz/gallon, how can I convert this to a specific gravity type reading. e.g. 1.025?

Thanks

AD

what kind of hydrometer is it?

you can get a really inexpensive one, like instant ocean for $5 to $6.

tdwyatt · 06-03-2005, 11:43 PM

There are several specialized types of hydrometers used for beer making, cider making, metal plating, and honey evaluations that measure SG in terms of the amount of the specific substance (in oz/gal) they are made for. Depending on the original indication of the hydrometer, the calibration will be for alcohol, sugar, any number of metals (I hope this is NOT one of the hydrometers you're using in your tank...), or organic acid content. These are not for use in aquaria for a number of reasons. Although there is a means of converting each of these types into their metric S.G. reading, we would need to know what the hydrometer was originally intended for and possibly the original manufacturer to give you the conversion factors. Unless this unit has a thermometer included or has automatic temperature correction, it may also require a conversion chart for temperature adjustment of the SG readings for the temperature of the liquid being measured.

You would be much better off getting either a refractomerter (best) or a swing arm hydrometer (cheapest) or an ATC bulb hydrometer (most accurate) made for comparison of aqueous liquids calibrated to 75 to 80 degrees F (and you still may need a temperature conversion chart for some brands of bulb hydrometers).

HTH, dump the one you've got now.

tdwyatt · 06-03-2005, 11:49 PM

btw, my FAVORITE REFERENCE for specific gravity:

M. Manning, "Understanding Specific Gravity and Extract," BrewingTechniques 1 (3), 30-35 (1993).

tdwyatt · 06-03-2005, 11:53 PM

WOW!!!

I ACTUALLY found this article on the internet!!!:

Brewing Beer and SG link (repaired)

tims · 06-04-2005, 07:15 AM

tom i can not get your link to work?.

tims · 06-04-2005, 07:16 AM

http://www.brewingtechniques.com/lib...1/manning.html

Tim224DT · 06-04-2005, 11:51 AM

http://www.brewingtechniques.com/lib...3/manning.html

I think tdwyatt might of been trying to post this article.

Tim

Tasher80 · 06-04-2005, 04:13 PM

Tdwyatt is right. I would get an ATC Refractometer. You can pick them up online for about $50. They are much more accurate than any hydrometer. Its a worth while purchase in the long run.

tims · 06-04-2005, 05:42 PM

try our sponor Ichity and things.. they have one for 56$ or so

tdwyatt · 06-04-2005, 06:08 PM

Thanks for the catch guys, I have repaired the link to the beer brewing hydrometer stuff.

Back on topic, many of the specialized hydrometers for these processes make working with these solutions much easier than having to do the calcs to adjust sensitive processes that require a specific gravity adjustment to produce the finished product, but they are of little use outside those areas of specialty.

HTH