Rusto,
From the product information sheet for Cutrine Plus:
Restrictions & Regulatory Information
Waters treated with this product may be used for
swimming, fishing, further potable water treatment,
livestock watering or irrigating turf, ornamental plants or
crops after treatment.
Do not use in waters containing Koi and hybrid goldfish.
Not intended for use in small volume, garden pond
systems.
I would STILL wait a day or two before swimming.
Also, esshup has a post (2/26/21) in this thread on his treatment protocol with the koi in his pond. I would hate for you to lose your old happy koi!
Good luck,
Rod
