Saltwater formulas

[peterac]

Hi all,

I have been in search of a formula or formulas to calculate a desired sg of saltwater given a known volume of water. Does anyone have one handy?

I use Oceanic (the blue bucket) which gives a rough starting formula of 1/2 cup of salt per gallon to achieve normal sg, but often I want to mix up 1.009 for doing water changes in my QT while doing Hypo. The amount of water in my mixing container could be anywhere from 20 to 80 gallons.

I know its not a big deal and I can slowly add salt until I get the desired result, but when you are doing alot of water changes it gets anoying to have to constantly check sg if you are not close to start with.

Thanks,
Pete R.

 

[rayjay]

I'm sorry but there is NO formula to give you the exact water and salt to come up with an exact s.g..
Every salt is different so that is a big problem in itself, and, I've found slight variances when mixing even different pails of the same brand. (I think coarser or finer affects the volume of salt slightly)
Best thing you can do would be to take a given volume of the salt you use, and mix it up to the s.g. you wish to have, and find out how much water it takes to get as close as you want to that s.g..
I do it slightly different and add a certain weight of the salt as measured on my balance scales, and add to a given volume of water.
Of course, you would want to do this for all s.g. ranges you use, or, you could make up the normal batch at the s.g. you most use, and then mark down how much to dilute a given volume of the main s.g. to get any of the other s.g.s that you wish to use.
I would still verify each and every time after mixing though, especially when treating with hyposalinity.