Thank you Tom this is just what I was looking for. it was very straight forward I thought it would be more complicated, Im almost ashamed that I had to ask

Well now that my self-esteem is low I might as well ask another question ( it's past midnight here now so I can always blame my stupid question on that )

Could any tell me how to obtain 1.035 salinity from any salt say e.g. Red Sea Coral Pro. The instructions only explain "normal" salinity mixing ( 1.021 - 1.025).

I guess its the same for all brands and how to calculate it depends on the dosing. But could someone please explain it ?

I thought it would be as simple as say:

from the bucket info:

1.021 requires 33.4 g /litre

1.023 requires 36.0 g /litre

1.025 requires 38.2 g /litre

so now I thought just take 33.4 divided by 21 and you get gram / salinity point (0.001)

So I tried 33.4 / 21 = 1.59047619

so I make a reference calculation to obtain 1.025:

1.59047619* 25 =39.7619048

and on the bucket it says 38.2

Please help me out with this one as well.

And thanks again for the help before ( I appreciated all replies, however Tom had he answer I needed so thanks again).