concrete stain

I'm making one of those concrete mold patios.It will come right up to my ponds.I made a section and its blinding white,not at all natural looking .I'm using the field stone mold and I want to stain it and use a sponge to apply different colors so it will look more like rock.Since the colorant is a ridiculous price and the patio is quite large we had decided to use concrete stain.
I have googled it and came up with stains and acid stains
Whats the difference between them?
Would it be harmful to use acid stain so close to the pond?
I want a more translucent look,not painted........