'Marine' salt mix for BW tanks: are we getting ripped off?

[js97]

Well I just want to start by saying i'm posting here instead of the Marine tank as this looks like it would apply more to BW setups.
I came across this trying to do some research :

http://www.fao.org/docrep/field/003/AB920E/AB920E00.htm

In short, the study in the link states that they found no statistical difference in the success rate of breeding shrimp with different sources of salt mixtures for their brackish water environment.
4 Types included:

• A mix of actual Sea water and fresh
  Fresh water and local 'Rock Salt'
  Fresh water and 'sea salt'
  Fresh water rock salt brine and salt stock solution

All taken to 20-30 ppt

So does this mean we can use some organic/pure sea salt/rock salt from the local grocery store? and pay half the price?

I realize that they supposedly add 'trace elemnts' (commercial products like 'instant ocean' etc.) but are these trace elements even necessary? it's not like they're coral.

it's backed up by the UN Fisheries and Aquaculture.

Any thoughts?

[Nick]

That article is about starting freshwater prawn larvae that happen to spawn in brackish water. It's very old, circa 1980, I think there would be followups if it were actually useful technique for anything other than rearing prawn. I'm pretty sure rearing prawn larvae is kind of like hatching brine shrimp - as long as the specific gravity is ok to trigger the right processes, the exact mineral balance isn't very important. These animals are in the brine for only 18 days, before becoming freshwater animals that don't need any salt. This is the opposite of many brackish animals, who's need for minerals is much greater as they age.

[Pufferpunk]

Try this one instead:
http://www.aquariumboard.com/forums/articles/4770.htm