Carbon can leech but not under conditions that fish can live in so no worry there. Used carbon really won't affect meds of any sort. And carbon lasting a week would be a miricle.
Will it hurt to use carbon, not at all. But it will hurt the pocket book if you want to use carbon to its full advantage as that would mean new carbon each week. And frankly weekly large water changes will do most things that carbon does anyway.
Will it hurt to use carbon, not at all. But it will hurt the pocket book if you want to use carbon to its full advantage as that would mean new carbon each week. And frankly weekly large water changes will do most things that carbon does anyway.