What Specific Gravity do you keep?

[Reef Stallion]

I would caution that this may not be correct. Perhaps the measured sg changes with temperature using some devices (like a hydrometer that is measuring density (which does change with temp) and trying to report sg), but the actual sg of seawater does not change much at all over the range of temps we encounter.

There is also almost no relationship between salinity (in ppt) and temperature.

Thanks for your reply Randy! I guess that I was misled by this article I read.
http://marinebio.org/oceans/temperature/
I guess that they should have used better references than Wikipedia. It sounded very scientific to me so I believed it.

 

[revhtree Verified Admin]

 

[danknuc]

1.024 @80

 

[gotwins86]

1.025 @ 78

 

[hybridazn]

1.024-1.026 77.5-79.5 degrees

 

[jason2459]

35 PSU

Calibrated via Randy's articles

https://www.reef2reef.com/threads/does-your-calibration-solution-need-calibrated.250133/

 

[jason2459]

Thanks for your reply Randy! I guess that I was misled by this article I read.
http://marinebio.org/oceans/temperature/
I guess that they should have used better references than Wikipedia. It sounded very scientific to me so I believed it.

Density can change and is more dense at the deep water columns in the oceans. We don't mimic those extremes (atmospheres or temps) and keep to surface level averages which is fairly consistent.

I highly recommend a book by Pilson
An Introduction to the Chemistry of the Sea.

It's available on Kindle too. Very much worth it and you don't have to be a Chemsitry professor to understand it.
https://www.amazon.com/gp/aw/d/B00ADP71PO/ref=tmm_kin_title_0?ie=UTF8&qid=&sr=

 

[FarmerTy]

1.026 at 81

 

[FishLover01]

I just keep my specific gravity anywhere from 1.024-1.026. My temps average about 80F. I've had the tank for a couple of years and it's been very stable. I never top off the tank. I do anywhere from 10%-25% water changes every week depending on how my nitrate readings are. If my nitrates are higher, I'll do a larger water change but never more than 1/3 of tank volume. These specs has worked for me well, so I've never went outide of these ranges but like everything else in this hobby, somebody else might have SG at 1.020-1.023 and have even a better tank.

 

[hawkinsrgk]

I have been keeping my temperature between 80-81 and salinity at 35. Does that mean my salinity is too low?

 

[jason2459]

I have been keeping my temperature between 80-81 and salinity at 35. Does that mean my salinity is too low?

What do you use to check the salinity? If it has automatic temperature compensation (ATC) you're most likely fine depending on how you calibrated the device.

If the device doesn't support ATC then you need to calibrate and test at its rated temp.


I would read Randy's articles I linked to in the link I posted in this thread and JimWelsh's thread that is also linked to is highly interesting.

35 PSU

Calibrated via Randy's articles

https://www.reef2reef.com/threads/does-your-calibration-solution-need-calibrated.250133/

 

[Sistawolf]

1.024 78.5 degrees

 

[Joey waid]

1.025-1.026 at 78...

 

[madweazl]

1.0255 for me. The ATO actually keeps it between 1.0255 and 1.026.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for your reply Randy! I guess that I was misled by this article I read.
http://marinebio.org/oceans/temperature/
I guess that they should have used better references than Wikipedia. It sounded very scientific to me so I believed it.

They discuss density (I saw no mention of specific gravity).

Water density does change a lot with temp (which is what a hydrometer actually measures and why floating glass ones need to be used at their calibration temp).

But specific gravity is the ratio of the seawater density to the density of freshwater at the same temp.

The change in density of the seawater with a temp change is almost the same as the change in density of freshwater with a temperature change, so specific gravity itself (beign the ratio of the two) does not change a lot with temp changes.

 

[Reef Stallion]

They discuss density (I saw no mention of specific gravity).

Water density does change a lot with temp (which is what a hydrometer actually measures and why floating glass ones need to be used at their calibration temp).

But specific gravity is the ratio of the seawater density to the density of freshwater at the same temp.

The change in density of the seawater with a temp change is almost the same as the change in density of freshwater with a temperature change, so specific gravity itself (beign the ratio of the two) does not change a lot with temp changes.

I just keep learning. Even after 20 years! Thanks!

 

[120reefkeeper]

[email protected]

 

[Ken Williams]

1.026 81

 

[prinaudo]

1.025 @ 78

 

[DebbieCorker]

1.022, 76 sometimes the salinity a tad lower but it's a sea horse mixed species tank and I try to keep it identical to the fry tank to ease the transfer after birth.