salinity levels
- Thread starter huffnpuffer
- Start date
BaNDiTo_RoX
Experienced Reefer
- Location
- Brooklyn/Puerto Rico
salinity should be @ 1.025 @ the highest. But lets see what others might say
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BaNDiTo_RoX
Experienced Reefer
- Location
- Brooklyn/Puerto Rico
surely you mean specific gravity not salinity as there is a difference. salinity should be about 34-38 and is not subject to fluctuations with temperature specific gravity however fluctuates with temperature and should be taken into acount. though related the terms are definatly not interchangable.
IMO a tank containing inverts should be kept at a salinity between 34 ppt and 38ppt with a specific gravityfalling between (based on temperature) 1.024 at 78 degrees to 1.027 at 83 degrees. but in the long run SG should be ignored and parts per thousand should be the quantative amount, unfortunatly the Myth-information of the SG range is so prevalent in this hobby that few ever figure it out.
- Location
- Philippines
wHat do you mean by tHat :scratch:
salinity is the measurment of salt in parts per thousand, specific gravity measures the overall density of the water, and water being prone to density fluctuation with temperature will change your results of a specific gravity test with temperature.
example. a "true specific gravity" of 1.024 (all hydrometers are calibrated at 60degrees f. so we shall call that "true specific gravity" for this example) when read at 79degrees f. will actually read on a hydrometer as 1.0263 and the same "true specific gravity" of 1.024 will read at 85 degrees f. as 1.0272 as you can see all these measurements are very different but come from the same water at different temperatures but of the same salinity. while no matter what the temperature the salinity in PPT will never change as there are only so many salt molecules in the water regardless of the temperature.
try it with a salt mix bucket next time you make water. make the water at room temp test the SG then add a heater to the bucket and retest the water after a signifigant change in temperature, you will get a different SG.
example. a "true specific gravity" of 1.024 (all hydrometers are calibrated at 60degrees f. so we shall call that "true specific gravity" for this example) when read at 79degrees f. will actually read on a hydrometer as 1.0263 and the same "true specific gravity" of 1.024 will read at 85 degrees f. as 1.0272 as you can see all these measurements are very different but come from the same water at different temperatures but of the same salinity. while no matter what the temperature the salinity in PPT will never change as there are only so many salt molecules in the water regardless of the temperature.
try it with a salt mix bucket next time you make water. make the water at room temp test the SG then add a heater to the bucket and retest the water after a signifigant change in temperature, you will get a different SG.
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- Location
- Melville, NY
I completely understand the difference b/t SG and salinity. My question then is how does a standard ATC refractometer that has both SG and salinity readings on it accurately tell the tale? Its the same line, not two different readings.
the specific gravity reading is superflous on a refractometer and should be disregarded.
All the ATC does is adjust the refractive line or prism to adjust for the refraction changes in density of water when subject to variant temperature, this only gives a true reading on salinity and in no way accuratly shows specific gravity no matter what the company that produces it claims.
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- Location
- Melville, NY
So in other words, it gives you an accurate salinity reading and the corresponding SG in the "true" world, not what the actual SG is based on current water temp?
if it were truly to work the way most manufacturers claim it does then the ATC refractometers would have an inversly expanding and contracting scale that spread and contracted with temperature variances giving a reading of 35ppt on one side no matter what the temperature (assuming thats the waters PPT) and a SG scale that slides seperatly to compensate temperature giving you your SG of 1.024 anywhere to 1.026 (this is the rough range of SG most peoples reef temps would fall within for 35ppt salinity) .
exactly your getting the SG your tank would be if the water was 60 degrees.
so in turn if your using a hydrometer that can only measure specific gravity NOT salinity despite what the unit says, your getting a temperature accurate reading but not a "60degree true" SG your salinity would then be skewed because you cantt measure PPT through density its just not possible.
and I must admit most people dont know and dont care in relative terms the measure ments are somewhat close so it may or may not ever become a factor. I just felt some clarification on the salinity Sg thing was in order as often they get freely interchanged and they are related but definatly not the same.
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- Location
- Melville, NY
Its so nice when someone explains it so eloquently. Thanks Reef!!:givebeer:
now back to the original poster you want a salinity of 34-37 ppt for anytank containing inverts for their optimal health. for ease of your fishes osmoregulatory process I reccomend a salinity of 35 and no higher. as salinity increases it costs the fish more energy to osmoregulate. so the happiest medium for both fish and inverts would be NSW levels (aka 35 ppt)
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