10, 20 or 30 % mortality is not important.
After all it is part of NATURE to die.
BTW 0 % mortality is quite suspicious, imo, like not tasting iodine????
Instead, it would be great to know the reasons of their death.
Too crowded?
Water leaking?
Food poisoning?
Water filtering not efficient?
or simply sharing the tanks with other species eating the shrimps.
Clarity please, like their claimed water.