density / temprature table ,does someone have one ?

tntneon · 09/29/2009, 04:40 AM

-Hi reefers ,

-I have the opportunity to measure s.g. at work in a lab , unfortunely the density device first heats/cools the sample to 20.00 degrees C (celcius) and then it measures the density very accurate (0.0001).

Now my water is usualy 26 degr. C , is there somebody who has a temprature vs. density table of sea water ?

It would be very helpfull for me if i had one

, now the device measures 1.0255 s.g. @ 20 degr. C , i guess the real s.g. would be lower then at 26 degr. C, 1.0240 perhaps ?

greetingzz tntneon

Randy Holmes-Farley · 09/29/2009, 05:00 AM

Edited:

it will be easier to post a table, which I'll find later, or someone else can post.

tntneon · 09/29/2009, 05:08 AM

thx Randy

,
Great info
Nice to hear you back , here on the forum !

greetingzz tntneon

Randy Holmes-Farley · 09/29/2009, 05:15 AM

OK, this is better:

use this calculator to get to salinity

http://www2.sese.uwa.edu.au/~holling.../denscalc.html

If you want sg, use table 1 here:

http://reefkeeping.com/issues/2004-06/rhf/index.php

tntneon · 09/29/2009, 05:48 AM

great info

it`s still a big difference i think ,if i read the curve correctly.
1.0255 @20 degr.C----> 1.02387 @ 26 degr.C
Then if have to add some more seawater (artificial mixed red sea pro) into my system.

greetingzz tntneon

Randy Holmes-Farley · 09/29/2009, 07:06 AM

Yes, that's why I edited the first post. It is enough to worry about.

Boomer · 09/29/2009, 02:28 PM

D^2

Boomer · 09/29/2009, 02:39 PM

Hi Randy bought time you are back

tnt

You cannot use this calculator that Ranyd posted
http://www2.sese.uwa.edu.au/~holling.../denscalc.html

as it is a Density calculator and not a Sg calculator. Density and Sg are not the same thing and is why your numbers are off

You need to use this calculator

http://www.reefkeeping.com/issues/20...conversion.htm

In the first 2 boxes type in 20C as that is the cal temp of the hydrometer. In the second box type in the tank temp, 26C. Then type in what the hydrometer reads in the tank. Do not cool or heat the sample. A 20C @ tank 26 C a reading of 1.0249 = 35 ppt

Randy Holmes-Farley · 09/29/2009, 02:41 PM

You cannot use this calculator that Randy posted
http://www2.sese.uwa.edu.au/~holling.../denscalc.html

as it is a Density calculator and not a Sg calculator. Density and Sg are not the same thing and is why your numbers are off

I told him to use the calculator to get density (which is what his unit reports), then my table to get to sg.

cccapt · 09/29/2009, 02:48 PM

Looks like the new software fixed Randy's stuck post count.

Randy Holmes-Farley
Club 65535

Posts: 65,555

Boomer · 09/29/2009, 02:56 PM

Ok it does read as he has an actual density meter then and not a Sg meter. I guess I just see to many posts listing density as if it is they are same thing as Sg

To make things worse many Euro -reefers actually do use density hydrometers.

Yes Larry I saw that also

tntneon · 09/30/2009, 05:25 AM

I first i used the calculator and then this curve to check my readings of the calculator .

And i came to the result that 1.0255 gr/cm3 @ 20 degr.C ==>1.0238 gr/cm3 ,
or am i wrong ?

@boomer :

I thought that s.g. was the same as density , they are both mass/volume numbers or not ?

If not what kind of density (gr/cm3) do i need to match an s.g. of say 1.026 ?

greetingzz tntneon

Randy Holmes-Farley · 09/30/2009, 06:20 AM

This article explains the difference between sg and density:

Specific Gravity: Oh How Complicated!
http://www.advancedaquarist.com/issu.../chemistry.htm

So in your case, use the density at 20 deg C to get the salinity on the calculator. Then use that salinity in my linked table (or other tables) to get to the specific gravity.

Or, you can just take the measured density at 20 deg C and divide by the density of pure fresh water at 20 deg C (0.998206 g/cm3) and get the sg at 20 deg C, which will be very close to sg at other temps in reefing.

Boomer · 09/30/2009, 09:57 AM

Randy's article should explain all to you. For many years we have tried and the reason behind Randy's article, to explain that D is not the same thing as Sg. It has not been an easy task.

D= M /V

Sg = mass off a sample/ mass of pure water at the same vol.

Here is some more on Sg vs D

http://www.simetric.co.uk/si_water.htm

The only time D= Sg is if one is using a Sg Hydrometer calibrated to 4C. To this day I have never found such a hydrometer. Sg Hydrometers are cal @ 15 C 20C, 25C and 25.5C. 15C is said to be Lab std. 20C is usually used for soils. In this hobby it is 25C or 25.5 C. When using a hydrometer for D or Sg you always need to correct for temp if the sample water is not at the cal point of the hydrometer. D is a dimensional unit as it is in g/cm^3, i.e., 1.025 g/cm^3. Sg is a dimensionless unit 1.0221.

The std Sg of seawater @ 25C = 1.0264 and D = 1.0233 g /cm^3 = 35 ppt.

So in your case, use the density at 20 deg C to get the salinity on the calculator. Then use that salinity in my linked table (or other tables) to get to the specific gravity.

What Randy is showing here is that @20C D = 1.02476 g/cm^3 = 35 ppt. Then from his table Sg = 1.0264.

More on Sg and D
Temperature Corrections for Hydrometers
http://reefkeeping.com/issues/2004-07/rhf/index.php

Here is Randy's larger table. If D = 1.02412 g/cm^3 @ 20 then S = 34.15 ppt. Go to the 25 C line and look up the Salinity. On that 25 C line 34.15 ppt, Sg = ~ 1.02458

acrylic_300 · 09/30/2009, 10:39 AM

Word problem:

My hydrometer is calibrated at 77 degrees F. My tank temperature is 83.5 degrees F. My SG "reading" is 1.0264.

What is my real SG?

I tried the various calculators and they wouldn't work (maybe my browser is broken).

Boomer · 09/30/2009, 12:04 PM

Your salinity is ~ 36.6 ppt, a little to high. You need that hydrometer to read 1.0251 = 35 ppt @ 83.5 F

Look at the table above. Go to the Sg column on the left and find 1.0264, then go across till you hit the 28.5 C line = 36.69 ppt. Now go up the column on that line till you find 35 ppt, then go to the left all the way across till you hit the Sg, 1.0251. (actually in between 1.025 and 1.0252)

In short just go to the 28.5 column and look for 35 ppt and then go all the way to the left to see what the Sg is, that is you target Sg. 1.0251 for 83. 5 F to get an equal 1.0264 @ 35 ppt NSW

tntneon · 09/30/2009, 12:05 PM

Quote:

Originally Posted by Boomer

Randy's article should explain all to you. For many years we have tried and the reason behind Randy's article, to explain that D is not the same thing as Sg. It has not been an easy task.

D= M /V

Sg = mass off a sample/ mass of pure water at the same vol.

Here is some more on Sg vs D

http://www.simetric.co.uk/si_water.htm

The only time D= Sg is if one is using a Sg Hydrometer calibrated to 4C. To this day I have never found such a hydrometer. Sg Hydrometers are cal @ 15 C 20C, 25C and 25.5C. 15C is said to be Lab std. 20C is usually used for soils. In this hobby it is 25C or 25.5 C. When using a hydrometer for D or Sg you always need to correct for temp if the sample water is not at the cal point of the hydrometer. D is a dimensional unit as it is in g/cm^3, i.e., 1.025 g/cm^3. Sg is a dimensionless unit 1.0221.

The std Sg of seawater @ 25C = 1.0264 and D = 1.0233 g /cm^3 = 35 ppt.

So in your case, use the density at 20 deg C to get the salinity on the calculator. Then use that salinity in my linked table (or other tables) to get to the specific gravity.

What Randy is showing here is that @20C D = 1.02476 g/cm^3 = 35 ppt. Then from his table Sg = 1.0264.

More on Sg and D
Temperature Corrections for Hydrometers
http://reefkeeping.com/issues/2004-07/rhf/index.php

Here is Randy's larger table. If D = 1.02412 g/cm^3 @ 20 then S = 34.15 ppt. Go to the 25 C line and look up the Salinity. On that 25 C line 34.15 ppt, Sg = ~ 1.02458

Thx boomer , great info , i learned a lot here !!!

Boomer · 09/30/2009, 12:06 PM

As Randy always says "You're Welcome

"

09/29/2009, 04:40 AM	#1
tntneon SPSahollic Join Date: Jun 2008 Location: terneuzen , netherlands Posts: 875	density / temprature table ,does someone have one ? -Hi reefers , -I have the opportunity to measure s.g. at work in a lab , unfortunely the density device first heats/cools the sample to 20.00 degrees C (celcius) and then it measures the density very accurate (0.0001). Now my water is usualy 26 degr. C , is there somebody who has a temprature vs. density table of sea water ? It would be very helpfull for me if i had one , now the device measures 1.0255 s.g. @ 20 degr. C , i guess the real s.g. would be lower then at 26 degr. C, 1.0240 perhaps ? greetingzz tntneon __________________ May the flow be with you ! Current Tank Info: 154 G SPS dominated + 25 G sump ; lighting : 210 W LED XPG/XRE (sunrise) + 150 W T5 (bl+ , 15°K , fiji , bl+) ; skimmer : Royal Exclusive supermarine 200 ; BM 3-Ch dosing pump (CA/ ALk and top-off) ; tunze 6085 circulation

09/29/2009, 05:00 AM	#2
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	Edited: it will be easier to post a table, which I'll find later, or someone else can post. __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef Last edited by Randy Holmes-Farley; 09/29/2009 at 05:07 AM.

09/29/2009, 05:08 AM	#3
tntneon SPSahollic Join Date: Jun 2008 Location: terneuzen , netherlands Posts: 875	thx Randy , Great info Nice to hear you back , here on the forum ! greetingzz tntneon __________________ May the flow be with you ! Current Tank Info: 154 G SPS dominated + 25 G sump ; lighting : 210 W LED XPG/XRE (sunrise) + 150 W T5 (bl+ , 15°K , fiji , bl+) ; skimmer : Royal Exclusive supermarine 200 ; BM 3-Ch dosing pump (CA/ ALk and top-off) ; tunze 6085 circulation

09/29/2009, 05:15 AM	#4
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	OK, this is better: use this calculator to get to salinity http://www2.sese.uwa.edu.au/~holling.../denscalc.html If you want sg, use table 1 here: http://reefkeeping.com/issues/2004-06/rhf/index.php __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

09/29/2009, 05:48 AM	#5
tntneon SPSahollic Join Date: Jun 2008 Location: terneuzen , netherlands Posts: 875	great info it`s still a big difference i think ,if i read the curve correctly. 1.0255 @20 degr.C----> 1.02387 @ 26 degr.C Then if have to add some more seawater (artificial mixed red sea pro) into my system. greetingzz tntneon __________________ May the flow be with you ! Current Tank Info: 154 G SPS dominated + 25 G sump ; lighting : 210 W LED XPG/XRE (sunrise) + 150 W T5 (bl+ , 15°K , fiji , bl+) ; skimmer : Royal Exclusive supermarine 200 ; BM 3-Ch dosing pump (CA/ ALk and top-off) ; tunze 6085 circulation

09/29/2009, 07:06 AM	#6
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	Yes, that's why I edited the first post. It is enough to worry about. __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

09/29/2009, 02:28 PM	#7
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	D^2 __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be. Last edited by Boomer; 09/29/2009 at 02:40 PM.

09/29/2009, 02:39 PM	#8
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Hi Randy bought time you are back tnt You cannot use this calculator that Ranyd posted http://www2.sese.uwa.edu.au/~holling.../denscalc.html as it is a Density calculator and not a Sg calculator. Density and Sg are not the same thing and is why your numbers are off You need to use this calculator http://www.reefkeeping.com/issues/20...conversion.htm In the first 2 boxes type in 20C as that is the cal temp of the hydrometer. In the second box type in the tank temp, 26C. Then type in what the hydrometer reads in the tank. Do not cool or heat the sample. A 20C @ tank 26 C a reading of 1.0249 = 35 ppt __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be. Last edited by Boomer; 09/29/2009 at 02:53 PM.

09/29/2009, 02:41 PM	#9
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	You cannot use this calculator that Randy posted http://www2.sese.uwa.edu.au/~holling.../denscalc.html as it is a Density calculator and not a Sg calculator. Density and Sg are not the same thing and is why your numbers are off I told him to use the calculator to get density (which is what his unit reports), then my table to get to sg. __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

09/29/2009, 02:48 PM	#10
cccapt Registered Member Join Date: May 2004 Location: N.E. PA Posts: 842	Looks like the new software fixed Randy's stuck post count. Randy Holmes-Farley Club 65535 Posts: 65,555 __________________ /Larry Current Tank Info: 125 reef

09/29/2009, 02:56 PM	#11
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Ok it does read as he has an actual density meter then and not a Sg meter. I guess I just see to many posts listing density as if it is they are same thing as Sg To make things worse many Euro -reefers actually do use density hydrometers. Yes Larry I saw that also __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

09/30/2009, 06:20 AM	#13
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	This article explains the difference between sg and density: Specific Gravity: Oh How Complicated! http://www.advancedaquarist.com/issu.../chemistry.htm So in your case, use the density at 20 deg C to get the salinity on the calculator. Then use that salinity in my linked table (or other tables) to get to the specific gravity. Or, you can just take the measured density at 20 deg C and divide by the density of pure fresh water at 20 deg C (0.998206 g/cm3) and get the sg at 20 deg C, which will be very close to sg at other temps in reefing. __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

09/30/2009, 09:57 AM	#14
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Randy's article should explain all to you. For many years we have tried and the reason behind Randy's article, to explain that D is not the same thing as Sg. It has not been an easy task. D= M /V Sg = mass off a sample/ mass of pure water at the same vol. Here is some more on Sg vs D http://www.simetric.co.uk/si_water.htm The only time D= Sg is if one is using a Sg Hydrometer calibrated to 4C. To this day I have never found such a hydrometer. Sg Hydrometers are cal @ 15 C 20C, 25C and 25.5C. 15C is said to be Lab std. 20C is usually used for soils. In this hobby it is 25C or 25.5 C. When using a hydrometer for D or Sg you always need to correct for temp if the sample water is not at the cal point of the hydrometer. D is a dimensional unit as it is in g/cm^3, i.e., 1.025 g/cm^3. Sg is a dimensionless unit 1.0221. The std Sg of seawater @ 25C = 1.0264 and D = 1.0233 g /cm^3 = 35 ppt. So in your case, use the density at 20 deg C to get the salinity on the calculator. Then use that salinity in my linked table (or other tables) to get to the specific gravity. What Randy is showing here is that @20C D = 1.02476 g/cm^3 = 35 ppt. Then from his table Sg = 1.0264. More on Sg and D Temperature Corrections for Hydrometers http://reefkeeping.com/issues/2004-07/rhf/index.php Here is Randy's larger table. If D = 1.02412 g/cm^3 @ 20 then S = 34.15 ppt. Go to the 25 C line and look up the Salinity. On that 25 C line 34.15 ppt, Sg = ~ 1.02458 __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

09/30/2009, 10:39 AM	#15
acrylic_300 Registered Member Join Date: Oct 2005 Location: Moberly, Mo Posts: 876	Word problem: My hydrometer is calibrated at 77 degrees F. My tank temperature is 83.5 degrees F. My SG "reading" is 1.0264. What is my real SG? I tried the various calculators and they wouldn't work (maybe my browser is broken).

09/30/2009, 12:04 PM	#16
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Your salinity is ~ 36.6 ppt, a little to high. You need that hydrometer to read 1.0251 = 35 ppt @ 83.5 F Look at the table above. Go to the Sg column on the left and find 1.0264, then go across till you hit the 28.5 C line = 36.69 ppt. Now go up the column on that line till you find 35 ppt, then go to the left all the way across till you hit the Sg, 1.0251. (actually in between 1.025 and 1.0252) In short just go to the 28.5 column and look for 35 ppt and then go all the way to the left to see what the Sg is, that is you target Sg. 1.0251 for 83. 5 F to get an equal 1.0264 @ 35 ppt NSW __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

09/30/2009, 12:06 PM	#18
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	As Randy always says "You're Welcome " __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.