Hi - not to second guess you, but are you confident there is cause and effect here? We have had some major power outages at my facility over the years and I've never had issues like that. Just checking that it couldn't possibly be flukes? They can leave the fish looking rather tattered.
So, assuming the fish are just banged up - slow healing by itself may not be a reason to dose antibiotics - I look for redness, white slime and/or increasing size of the lesions as my "trigger" to dose with them.
Have you read my article on medicated food? If so, then you also know I'm not a big fan of dosing antibiotics in Focus as the dose is totally uncontrolled. If you prepare your own food, the Kanaplex can be used at 50mg/kg fish body weight for 5 to 7 days. Amoxicillin can be dosed at 80mg/kg of fish mass, daily for 10 days. Cipro has also been used, but I don't know the dose. Metro is for protozoans and anaerobes, so I wouldn't use that.
Jay