Mixing Salt ...At What Temperature?

[Craig Lambert]

I'm setting up a new tank this Thursday and am just finishing up 80G of RODI, and plan to start mixing in salt this afternoon. I have it stored in Brutte cans located in my garage as I prefer to mix my saltwater outside of the tank. As in the past, my target for saltwater will be 1.026 and 80 degrees. To achieve this, is it best to raise the water temperature to 80 degrees prior to mixing? I'm assuming SG would measure differently at a lower temperature, and the SG level may go above my target if mixing is done at a lower temperature than 80 degrees. (I'm asking because my garage is around 40 degrees, so it's going to take a couple of extra heaters to keep the water at 80 degrees for 3 days).

 

[Randy Holmes-Farley]

I never warm my salt water above room temperature, which in my basement is often below 70 deg F. I change water very slowly with a Reef Filler dual head pump, so there is no need to match temperature. I gauge salinity with a conductivity meter, which is self correcting for temperature.

How are you measuring sg?

 

[Craig Lambert]

Thanks Randy,

I'm measuring SG with this refracometer:

http://www.marinedepot.com/md_viewItem.asp?idproduct=CP2111

I have not callibrated using your salt solution, but plan to do so.

The saltwater I'm mixing is not for a water change, but rather to set up an entire system. My rock arrives Thursday from a small vender I have purchased from in the past. It is fully cured fiji, and has been through 3 seperate curing tanks of his for the past 13 weeks. It will be overnighted to me Wednesday, so it will be out of the tank from 4PM Wednesday until it's in mine around noon on thursday. I mention this as my intent is to place the sand, rock and add the water to the tank, all at one time on Thursday morning. I did this 3 years ago, and my cycle lasted only 4 days. This is why I wanted the saltwater at 80 degrees prior to adding. Should I mix it at a lower temperature and then heat up just prior to adding it to the tank? Will SG remain the same if I mix at say 50 degrees, and then heat it to 80 degrees just prior to adding it to the tank on Thursday?

 

[Randy Holmes-Farley]

My understanding is that the sg/salinity as measured by a refractometer is corrected for temperature in that refractometer. So it should be OK to read it when cold. You can always test that by reading some cold, and then taking a bit inside, let it warm up, and measure again.

Will SG remain the same if I mix at say 50 degrees, and then heat it to 80 degrees just prior to adding it to the tank on Thursday?

The salinity does not change significantly with temperature. Specific gravity changes only a little bit, and the refractometer is not smart enough to know about such changes. But it is salinity that you really care about,

 

[Craig Lambert]

Thank You Randy!

 

[Randy Holmes-Farley]

You're welcome.

Good luck.