Quarantining New Plants
Why new aquarium plants carry pest snails, algae and pesticide residue, and how to isolate or dip them with bleach, alum or potassium permanganate.
Why quarantine plants
New plants can introduce unwanted hitchhikers into an established tank. The most common are pest snails and their eggs, but plants may also carry nuisance algae, and plants grown emersed at a nursery can carry pesticide or fertiliser residue. Quarantining or treating new plants reduces these risks before they reach the display tank.
Isolation method
The simplest approach is patience: keep new plants in a separate container away from the main tank for two to three weeks. This isolation period lets any snail eggs hatch where they can be spotted and removed, without exposing plants to chemicals. A slow, steady approach is often safer than aggressive dosing, since finding a dose strong enough to kill snails and eggs but gentle on delicate plants is difficult.
Bleach dip
A bleach dip uses unscented bleach diluted no stronger than 1 part bleach to 19 parts water. Sensitive plants are dipped for no more than about 2 minutes and hardier plants for about 3 minutes, then rinsed thoroughly in dechlorinated water. Bleach is harsh and does not reliably destroy all snail eggs, so an isolation period afterward is still advised.
Alum dip
Alum is regarded as one of the more effective treatments for snails and eggs while being gentle on plants. A soak of about one tablespoon of alum per gallon for up to a couple of days has been reported to kill snails and snail eggs without harming the plants; stronger solutions of a few tablespoons per gallon are used for shorter soaks of a few hours.
Potassium permanganate dip
Potassium permanganate is another option, used at a low concentration such as a few milligrams per litre, dipping plants for roughly ten to fifteen minutes, or a stronger purple solution for a shorter dip of around five minutes. Rinse plants well afterward before adding them to the aquarium.
After treatment
Whatever method is used, rinse plants thoroughly and, when snails are a concern, still keep the plants out of the main tank for two to three weeks to be sure no eggs survived. Inspect leaves and roots for snails before planting.