Medication's are last resort for me.(not everybody)
Recently aquired a young firemouth that developed cloudy eye's (2).
After a couple week's of twice weekly 50 perecent water changes,,the eye's are clear once again.
In any event.. making a paste of food/medication,abit of water, and getting the fish to eat same,,is better approach than treating water.(For me)
I have in the past, mixed equal amount's of crushed pill's /powder, with fish food, and a bit of water to make said paste ,and then freeze the mixture and break off chunk's for fishes to eat.
Help's to not feed the fish for three or four day's before feeding the medicated food and only feed the medicated food while treating.
Treating the water in isolation tank can work well also ,but I have had better luck (assuming fish is eating) with the medicated food .
I would try the twice weekly water changes first for a few week's ,maybe lower temperature a bit to slow any bacterial progression .