You bought the tank new and it busted? How long ago?
It's really unlikely it's fin rot if it just happened when your tank broke. More likely that they got damaged during the incident.
Reiterating pristine water and patience. Many polys have completely healed from torn fins, for example when another fish bites them. They're actually quite amazing that way.
Here you can follow my Delhezi's fin recovery from being attacked by another poly.
https://www.monsterfishkeepers.com/forums/threads/udons-tail-regrowth-progression.680518/
Jump to here to get to dates/photos without the story.
https://www.monsterfishkeepers.com/forums/posts/7694513/
Thank you for posting this! It makes me feel so much better

