With ich, I would recommend following Duncan's guidance, or do both. Ich has three stages, one of which is embedded in the skin of the fish and not susceptible to the treatments, a second is an egg stage which is again protected from treatments, but then the third is a free swimming stage which is the stage that the ich is susceptible to the treatments. Because of the time in each stage and its temperature dependence, the treatments need to be over a longer time frame. For ponds that do not have plants, I prefer salt as it does not lose strength over time, except by dilution with fresh water, and is easily measured with a salt meter or TDS meter.
Plants don't like salt at the level needed, and will die.
Zone 7 A/B
Keep your words sweet. You never know when you may have to eat them.
Richard