[bongobrian]

I wanted to post this pole as a sort of continuation of the "what's your ideal temperature" pole. Please post!

[fishpoo]

am i seeing right. 108 views and no replies. i think there's a record here.
mine is 1.026 at 80F

[Ironreef]

I use to range from 1.023-1.026 but my fish like a low salintity so I decided to keep it under/close 1.023 . doesn't seem to affect my corals.

[organicreefer]

not too many replies,but 30 or so votes,not bad just what i would expect,the majority at 1.023-1.026.
my ideal specific gravity is one that is STABLE,at a stable temp.

[bongobrian]

Hey FishPoo- I keep my levels pretty much the same as yours. I keep my salinity a little bit lower usually (1.025) for some reason the corals seem to open up more. Maybe it's just my imagination.

Everyone- do you think I set up this pole using the best ranges? or should have they been wider ranges like 1.023-1.026. I use a tighter range and I keep everything usually within one one-thousanth of a point. Should I not be so fussy?

[Randy Holmes-Farley]

FWIW, the sg (60 deg F/60 deg F) of natural seawater (35 ppt) is 1.0269.

Some people may come up with slightly different values for the last digit, but it is clearly in the highest section of the poll, where I proudly placed my lone vote!

[Ninong]

Originally posted by Randy Holmes-Farley
FWIW, the sg (60 deg F/60 deg F) of natural seawater (35 ppt) is 1.0269.

Some people may come up with slightly different values for the last digit, but it is clearly in the highest section of the poll, where I proudly placed my lone vote!

Randy,

Your answer may be confusing to some, which points out the futility of a poll asking for specific gravity numbers instead of salinity numbers.

If you are keeping your tank at 1.0269 SG, then you are obviously maintaining it at a much lower temperature than many others. Could you please tell us your tank's temperature so that we might have something to go on? Because a specific gravity of 1.0269 at a temperature of 81 degrees Fahrenheit would equal a salinity of more than 38 ppt.

Granted that natural seawater salinities in the areas of most coral reefs range from 34-36 ppt, except for areas that are impacted by nearby deserts, such as the Red Sea, the Persian Gulf and the Mediterranean, but are you saying that a salinity of 35 ppt at a temperature typical of equatorial coral reefs equals 1.0269 SG? Or are you saying that 1.0269 SG equals 35 ppt at a temperature of 16 degrees Celsius or approximately 60 degrees Fahrenheit?

I always thought that a specific gravity of 1.025 at a tank temperature of 81 degrees Fahrenheit would equal natural seawater salinity.

Again, this just points out how useless it is to ask for specific gravity numbers instead of salinity, since the specific gravity of a tank kept at 75 degrees Fahrenheit would be very different from that of a tank kept at 83 degrees Fahrenheit even though both might be at 35 ppt salinity.

Ninong

[bongobrian]

I think someone likes to hear themselves type.

[Randy Holmes-Farley]

Ninong:

< but are you saying that a salinity of 35 ppt at a temperature typical of equatorial coral reefs equals 1.0269 SG? Or are you saying that 1.0269 SG equals 35 ppt at a temperature of 16 degrees Celsius or approximately 60 degrees Fahrenheit? >

I maintain my tank at 35 ppt, which corresponds to a specific gravity (60 deg F/60 deg F) of 1.0269. Regardless of the temperature, if you use a hydrometer at the temperature at which it is designed, a reef tank with 35 ppt salinity will show a sg greater than 1.026.

What you are referring to is a hydrometers reading: the specific gravity changes little with temperature, while a hydrometer reading does. When you use a hydrometer at a temperature other than that which it is designed, the apparent hydrometer reading will drop as the temperature is raised. One can use tables to correct this problem and get a true specific gravity, but only if one knows both the measurement temperature, and the design temperature of the hydrometer (called the reference temperature).

FWIW, if you have a hydrometer designed to be used at 77 deg F (which I do) and you measure seawater at 77 deg F, the hydrometer reading will be approximately 1.0269.