I understand the caution, with regard to shrimp I would remove one individual from the tank and put it in a glass or container as a test subject with some of the tanks water to a known volume so that you can dose according to 1ml per 10L and then observe the response over 24hrs or so, you can run the experiment longer and increase the dosage. If I had doubts this is what I would do.
On a purely logical basis this is very sound advice (perfect scientific method), however, my few remaining shrimp deserve better. I just can't do it. On a more practical note they are impossible to catch!