Jake, I answered a similar question on APC a few weeks back I've copy & pasted it here for you since I think it also answers your question.
From:
http://www.aquaticplantcentral.com/forumapc/seachem/90267-copper-sulfate-flourish-shrimp.htmlI'm not a SeaChem representative but I can probably answer your question.
Copper sulfate is used as medication and can be harmful to shrimp when the concentration is high enough. That said, you can use copper sulfate as a source of copper at very low concentrations which is what flourish does (and so do nearly all other micro mixes on the market).
Copper toxicity (the LD50) for cherry shrimp is 0.37 ppm. If used correctly any copper based fertilizer you put in your tank should never get anywhere close to that level even when liberally over dosing (even 10-100x recommend dose levels).
To show you what I mean here is an example:
When using flourish comprehensive to get 0.5 ppm iron (the recommended EI iron dose) you add 0.0002 ppm copper from copper sulfate. This is from 53 mL of flourish comprehensive in a 90g tank. You'd have to add 1850x the recommended dose to reach 0.37 ppm (toxic level), that is equivalent to about 26 gallons of Flourish Comprehensive in a 90g tank.
If you'd like to figure out how much copper from copper sulfate you are adding with flourish or any other micro mix, check out
http://calc.petalphile.com/ it will show you every micro concentration in whatever sized tank and with all recommended dosing guides.
Basically the answer to your question is, there is absolutely NO risk to your shrimp from Flourish Comprehensive.