Just to finish this tread because a lot of people are seeing it. I did found out the problem. RCS are more sensible to any change then you can think. Most dyed because of water change. To fix that, buy a small pump, restrict the flow of the tub to the minimum. That will take time to fill up, if you have a 32 gallon like me. But you dont need to hold the tub. Found a way to hold your tub so that you can do something else.
I have copper tubing in my apartment. so i stope using prime because it do not specify copper, but fluvial shrimps safe do. Whats more amazing his, if you prepare your water in advance, (prime or shrimps safe)and keep you water fore more then 2 days, you will see in your barrel (white barrel helps to see it) of water a films that stick in the bottom. That stuff, his the reaction of the product you use to the neutralize hard metal like copper and chlorine.
Finally, ferilizer did not affect my shrimps when adding some in the morning. But having more then .7ppm of iron did kill them.
p.s. Removing they algae with, any product, even Hydrogen peroxide will kill your shrimps. Its not the Hp that kill them but the sudden Change.