I noticed you mentioned flash the 2nd time I skimmed the post, but I always look at pictures first then go back to go over the TEXT.
Most of the time when I get NEW shrimp the water tends to be in the 1000+ TDS, so it takes a while to match that to 200+ range.
I need to set aside a few of those clear Pyrex bowls next time I get a new batch. 2nd & 3rd picture you took with the flash came out well. SS's blue velvet shrimp match the edge of the Pyrex dish.
There's only 10 of the lower grades if you decide to try to "fish" them out. I find, if I drop a bamboo skewer or place anything in the tank, the shrimps will emerge from the jungle to investigate & climb whatever object like a ladder. Pretty neat.