But, see, that's what I have been trying to explain in terms of the way some of us treat with Prime -- that is, we remove our water during the change process, then add Prime according to the directions on the bottle, dosing for the amount of gallons the tank holds, and THEN go run the fresh water and return it to the aquarium where the Prime already had a chance to "take hold" in the water column...I don't believe anyone is saying you should add the new water WITHOUT the Prime in there FIRST if that's what you were getting at...
In other words -- I think what you're stating here above is that your Red Shrimp would die if fresh, untreated tap water was introduced to the tank BEFORE something like Prime was added, correct? If that's the case then yes, there COULD be some danger in adding fresh water to a tank with NO water treatment done whatsoever (though I really doubt the small amount of time it takes to refill whatever tank you have, unless it's RIDICULOUSLY huge and requires a lot of time to refill, would be of any dire, lethal consequence to the fish before you could get dechlorinator in there)...HOWEVER, what I am suggesting, and what many other Prime users do also, is that once the tank is drained of its percentage of water for the change, IMMEDIATELY pour in the Prime according to the volume of water in the tank and THEN add your fresh, clean tap water...