New arrival died, need help.

[NetBelleAnie]

I got some albino guppies in the mail on Thursday and one of them died a few hours ago.  Another one is showing similar symptoms with the split fin and some blood on the edges of the fins.  I'm pretty sure its fin rot, but as I was unable to set up a quarantine tank before hand (no room due to construction), so since none of my other tank mates (12 pygmy cories, 8 albino cories, 2 pygmy gourami, 1 bristlenose pleco, 6 amano shrimp and a bunch of ramshorn snails) have been medicated, I'm dosing the entire 55 gal.  The only thing I'm wondering if my ramshorn snails and amano shrimp will be able to survive the quarantine trio meds?

PH: 7.0
Nitrates: 10 ppm
Nitrite: 0
Ammonia: 0
GH: 300 ppm
KH: 60 ppm
Temperature: 75.5*F

[Fish Folk]

Yes, snails and shrimp should be fine. Bear in mind that sometimes fish are not a hardy genetic strain to begin with, and just cannot handle the transfer to a new aquarium.