Plant Dips/Baths for disinfecting plants and killing snails
The tip below is ONLY if you are concerned about snails. I actually suggest eliminating snails with 2 or 3 clown loaches, or puffer fish. These fish eat snails and will rid your tank of them.
NO aquarium plant distributor/nursery/wholesaler/retailer, can or will, "guarantee" their plants to be 100% snail free. Live aquatic plants and snails go together like peanut butter and jelly. So if you want to be 100% sure not to get snails simply treat your plants before putting them into your tank.
Below, I describe three dips, please pay attention to the words of caution also.
Potassium Permanganate Dip
The first dip is milder and safer for the plants. It is a Potassium Permanganate dip. Potassium Permanganate is available at Sear's and Ace Hardware in the area where they sell water softener's and supplies. You can also purchase Potassium Permanganate from chemical supply companies, both local and online.
To prepare a disinfectant dip, use a bucket filled about 1/2 full of water. Add enough Potassium Permanganate to color the water a dark pink. This solution can be saved if covered, and it's a great way to store your nets and tools, by soaking them in this solution. To disinfect and kill most snails, this also works for algae a 10-20 minute dip in Potassium Permanganate is very effective. After the dip Rinse the plants under tap water thoroughly and add dechlor to your tank...it neutralizes Potassium Permanganate.
CAUTION: Potassium Permanganate is a strong powerful oxidizer. Treatment should be made outside the tank...it will kill your bio-filter. Like all chemicals you should wear protective eye wear and gloves. Potassium Permanganate will stain clothing, carpeting, skin, etc. Never combine Potassium Permanganate and Formalin, this will result in explosive results and dangerous gases.
Bleach (Chlorine) Dip
This is a more effective and sure-fire way to kill snails and algae. It is also very easy to kill the plant in the process. Regular household bleach (i.e. Clorox) is diluted to a 5% (19 parts water to 1 part bleach) solution in a bucket. It's good to have a second bucket filled with rinse water containing 3X the normal dechlor. Dip large leaf plants for 3 minutes, immediately move to the dechlor rinse water, then rinse under running tap water for a few seconds, if you still smell chlorine, repeat the rinse process again. For small delicate leaf plants and mosses dip for only 2 minutes in the bleach. To be safe, add dechlor to the tank after adding the plants back. Also, if your dipping a lot of plants you may need to add more dechlor to your rinse water.
Remember, the bleach dip is a last resort solution. It can kill your plants! Use the same caution handling bleach as recommended for Potassium Permanganate.
Alum Dip
The Alum dip is more for killing microscopic bugs. Use at 1 tablespoon per gallon of water. Soak the plant for at least an hour, longer soaks of 2 to 3 days are needed to kill snails and snail eggs. For snails and snails eggs a 2-3 hour soak in a stronger solution of 3 tablespoons per gallon of water is a better choice. Alum isn't nearly as effective as the prior two for killing algae. Alum is aluminum sulfate and Alum USP can be obtained from a compounding pharmacy or grocery stores. (It's usually with the spices, herbs and pickling supplies).
If you already have snails? No problem, buy 2 or 3 small clown loaches or puffer fish and they'll take care of the snails and the eggs in short order.
You can also keep pond snails in check by taking a piece of cucumber and placing it in a small container where your fish can't get in the container but the snails can. Do this at night and in the morning many of the snails will go in the container to eat the cucumber and then you can just take the container out of the aquarium with the snails. This will keep the snail population in check.