This is just my experience but ive been using straight RO water for many years without supplements and all the shrimp i have kept have proliferated well. Good color, fast breeding, and what i assume is normal shrimp behavior. Snails however do no grow well, loose color, and live rather short life spans. Ive pondered that perhaps this is due the shrimps diet, that perhaps the mineral content in the water is not as important as the mineral content in their food. Only a thought from an uninformed aquarist.