Triops and Fairy shrimp

I got some Triops eggs from a local toy store a few weeks ago. In the instructions it says that you can't use dechloranated tap water. Do you guys know why that might be? I was thinking of using some aquarium water, but I am afraid that aquarium water might also not be suitable.
The instructions say: "Use purified bottled drinking water only", but what exactly is different? Surely not all brands of purified water have the same ammount of disolved minerals.
What do you guys think?

I also did get some Fairy shrimp eggs and they are busy hatching
I'm planning to feed them 'green water' and baker's yeast in a couple of days. Question is how food much is too much? Will a few drops be enough?

 

eish... donno - what about spring water?