Specific gravity, salinity, and temperature

[pro2k]

I have a question about the salinity reading of my reef tank. I think most people keep a salinity of about 32ppt or a density of 1.024. My question is since the density varies with temperature do you have to make a correction to the observed hydrometer readings?? What I'm saying is if my hydrometer says 1.024 and the temp is 76F is that really a salinity of 32ppt? (are the hydrometer calibrated for a temp around 76?)

[bjpembo]

what type of hydrometer do you have? is it one of the swing arm types? if so you'll need to read the directions and see what temp is calibrated for. i highly recommend you replace the thing though, they are every inaccurate. if you have a the floating type that looks like a big thermometer with a tube on the top of it the it should tell you what temp range its accurate at, these are very accurate but hard to use. i use a refractometer costs about 40-50 bucks off ebay is temp compensated and can be calibrated. will tell you exactly what your sg is.

[pro2k]

it's a Coralife Deep Six. I've had it for a year or so and don't have the directions. Looks like this : http://www.aquaticsbykr.com/images/testing/testinghydrometer.htm From this picture it seems to already temp calibrated for fairly accurate results.

[bjpembo]

that would be the swing arm style. here's a pic to show what im talking about, these are the same as yours just a different brand, they show different readings for the same tank water.

[BUGZME]

The best way to check salinity is with a good refractometer. The good ones will compensate for the temp. Best money I ever spent!