[Fin Rot on Red Eye Red Tail Puffer, please help!]

 Thank you, do you know of any alternative to Api Furan2 or API Fin and Body cure?  I can’t seem to find any locally or anywhere online.

[Fin Rot on Red Eye Red Tail Puffer, please help!]

I did the trio on the 1st day and started the full course Maracyn the next day. Here are some more pictures.

[Fin Rot on Red Eye Red Tail Puffer, please help!]

Wednesday I got a group of Red Eye Red Tail puffers from an online store. Two of them came with a white tip on the tail. I assumed it was fin rot and started treatment with Maracyn the same day. It doesn’t seem like the treatment is working. one of the puffers tails is about 30% white the other the white has worked it’s way to the tail body. I see it now on a 3rd puffer. Should I remove the infected puffers from the tank. Are there other meds I should use? Please help ! 
 

37 gal planted tank with co2 (fully cycled)

ammonium 0

nitrite 0

nitrate 20-30

ph around 7.4