Salinity

[squall7733]

Silly question.

I'm raising the temp of my tank while I'm cycling to make bacteria grow faster. When I lower the temp for the bimac, does the salinity of the tank go up or down as the water gets colder?

 

[main_board]

Salinity would remain constant, as long as you don't add or remove water with a different amount of dissolved salt. If you put a kg of salt into a tank and it all dissolves, increasing or decreasing the temperature isn't going to make the salt come out of solution nor make more dissolve. You've added a kg and no more or less can dissolve than that.

Generally, temperature has little to do with the amount of dissolved ions in a solution, though granted temperature change is used to supersaturate a solution, but thats well beyond the scope of aquariums. Hope that helped and didn't confuse.

Cheers!

 

[squall7733]

Ah, I thought that specific gravity would change with temperature.

 

[Feelers]

I believe that specific gravity does change with temp - based on my home distilling I know it affects the reading, so I think what happens is the reading will need to be adjusted for, just not the amount of salt in the tank lol. - could lead to problems
For my homebrew the sg comes with a table with a variety of temperatures.

 

[corw314]

When I redid my tank, which had been full of feeder crabs, the salinity was off the scale. Don't know how this happened as I only add fresh as evaporation occurs. Crabs seemed to be fine in it though.

 

[cthulhu77]

It does change slightly with temperature differentials, but only over a huge scale, not the small increments (+/- 3 degrees) that we work with...you should have nothing to worry about.

greg

 

[Colin]

The refractometer I have adjusts automatically to suit the temperature of the water to give an accurate reading.
Very usefull because I often make up my saltwater mixes in my garage which is cold and the water temperature is often about 50 - 55deg F whereas my tank is about 78... obviously I heat the water up before adding to tank but water temp does make a difference to a hydrometer's readings

 

[squall7733]

That is my concern. My tank is 83F right now and I'm going to lower it to 68-70F before my octo takes it as a home, so my reading will change greatly. However, I know that salinity is a little low right now. 1.023, and I want it to be 1.026 when I add him. Will it rise with lower temperature, or would it go down?