Mild antiseptic for pond

[batang_mcdo]

Hi,

Any suggested mild antiseptic that is good and safe on the Biological filter as well?
I'm keeping arowanas in my pond and there are some torn fins and minor wounds.

I've added salt to my pond, any other mild antiseptic that is recommended?
whats your opinion on melafix or tea tree oil?

I used to treat my arowanas before when they were still in aquarium, but pond is a little too big for my normal medicines.
will light PP dosage be a good disinfectant?

thanks.