The reason you probably heard it mentioned was for the sterilization. A 19:1 solution of water:bleach is just one method of sterilizing plants. I agree it is overkill. Usually bleach is reserved for severe cases of algae and only as a last resort.
Sterilizing new plants is usually a good idea. It is possible to introduce unwanted things into your tank on plants – like snails (if you don’t want them). Even ich can come in on a plant, if it was in a store with fish in the tank instead of a plant-only tank. Alum is a safer alternative for getting rid of snails and their eggs. You can buy it at drug or grocery stores. Use 1 tablespoon of alum per gallon of water. Soak 20 minutes to 2 hours. A two-day soak will kill snails and their eggs. Don’t use this on very fragile plants.
Another method for sterilizing is potassium permanganate, mixed at 10 mg/liter of water for a 10 minute soak. Will kill bacteria and pathogens. Potassium permanganate can be bought at chemical supply stores. Be careful, wear gloves and old clothes and towels on the floor, it will stain. “Clear Water” from Jungle Products contains potassium permanganate; use according to directions. It’s easier to work with.
Quarantining is the easiest method, all you need is a glass jar (or cheap plastic ‘critter container’) sitting near a window or under a desk lamp for 3 weeks. This eliminates parasites like ich because the free swimming parasites must find a host within a limited period of time or die. Also, you can tell within this timeframe if your plant did carry snail eggs and then treat with the alum only if necessary.
