Disinfecting Plants for the Home Aquarium

(by Sylphid August 29, 2002)

A three-part article describing various processes and products used to prepare aquatic plants before introducing them to the home aquarium.

PART I: Introduction

Ah, the tempting nature of lush green plants at the fish store!  Oh, how they wave gently in the current of the power filter… how they beckon and entice!  *drool*  How easy it is to buy them and take them home… and hold them gingerly between one’s fingers… and lift the aquarium hood… and lower them slowly into the… STOP!  Step AWAY from the aquarium!!!

 If you’re in any way like me, you probably can’t resist the lure of any healthy plant.  But before planting it in the aquarium, it’s very important to take the time to be sure that the plant isn’t carrying anything unhealthy.

The Importance of Disinfecting Plants

Disinfect a plant?  Absolutely.  Although most store tanks are generally very clean, any tank in any location has a lot more in it than one can actually see with the naked eye.  This goes for your own aquarium—who knows what’s lurking under the water and on the scales of your fish?  Many privately-owned fish store plants are actually cultivated and sold to the store by other local aquarists.  Properly cleaning and preparing a plant is particularly important if the plant is from an outside source, like a local lake or pond.

Some specific examples of nasty hitchhikers are snails and their eggs, fish and plant disease, and the very formidable Hydra.  Snails are not necessarily bad in any aquarium; when they become rampant, however, they can really take away from the aesthetic appeal when all a viewer can see is snails winding their trails across the front glass.  Again, snails are not a problem if you can keep the populations under control with any gastropod-loving fish that already lives in your aquarium.  But if you don’t have any such fish and your tank is already fully stocked, it can be very disruptive to the community to add them later.  Finally, any aquarist that has any little snails in the aquarium will tell you that—short of tearing down the tank—you will never completely get rid of them.

Fish and plant diseases can travel in active or dormant forms on unsuspecting plants.  If the plant is introduced while infected, the disease can spread into tank populations if conditions are right.  Hydra are small worms which eagerly compete with fry for food—and can even eat fry and some smaller fish.  Hydra grows quickly to become an unsightly problem in the right environment.

Disinfecting plants isn’t all work; it can be fast and very easy.  Ultimately, the thing to keep in mind when introducing new plants is to reduce the variety (and number) of extra elements that you’re bringing into your tank.  The risks of contaminating your entire aquarium far outweigh the minimal effort it takes to ensure the safety of all inhabitants.

PART II:     Solutions for Disinfecting

There are several methods with which to disinfect plants for home aquaria.  In this section I’ll outline the most common and convenient.

Keep a Quarantine Tank

A quarantine tank is an established aquarium specifically set-up for housing new plants and fish for a ‘holding period’ before introducing them to the main tank.  A quarantine tank is generally smaller than and separate from the community tank, and has minimal decorations.  The ‘quarantine’ method of inspecting plants offers the advantage that over time one will be able to identify a good number problems with very little effort.  For example, if you quarantine your plant and a week later the tank is rampant with snails, obviously the plant was infested with little snails and/or their eggs.  A quarantine tank can also be used as a fry tank or a hospital tank when there are no new articles to be quarantined.  Quarantining a plant also tempers an aquarist’s patience and allows him/her time to decide how to incorporate the new plant into the aquascape.

However, a quarantine tank has some distinct disadvantages: (1)  A quarantine tank, like any aquarium, requires space and maintenance.  For an aquarist with limited time and space it may not be a viable option.  (2)  A quarantine tank does not allow the identification of all nasties.  Some diseases in dormant form may not become evident until the plant comes into contact with fish later down the road.  (3)  A quarantine tank doesn’t actually treat or remove the hitchhikers.  The plants will still need to be cleaned.  And further, (4)  A quarantine tank requires patience.

Quarantining is an ideal solution for isolating new fish before adding them to the community, but for plants there are much better options available.

Potassium Permaganate

Potassium permanganate (chemical formula KMn04) is a very versatile compound with great qualities.  A particular large-chain drinking-water company uses it as a reactant in its patented processes for removing impurities.  Due to its damaging effects on bacteria, it is also frequently used in laboratories for cleaning glassware and other equipment.

Potassium permanganate has some great applications in aquaria, too.  This is recognized by the fact that several aquatic supply companies produce a ready-formulated disinfectant solution for consumer use.  As I am not granted any royalties as a spokesperson, I will not name these products by brand.  However, I will tell you that they are sometimes available at fish stores that also carry plants—usually the privately-owned stores.  If your local fish stores don’t carry any of these products, you can try a pharmacy or chemist.  Sometimes it can be purchased as an over-the-counter medical supply in the form of pink crystals.

Packaged aquarium products generally come with instructions (one would hope) and can be used according to the directions.  Most of them instruct soaking the plants for 10 to 15 minutes, then soaking in or rinsing with dechlorinated tap water.  If you purchase the product in crystal form from a chemist/pharmacist, you can drop a few into a tray of water.  You only need enough to make a pale pinkish solution.  Soak for 10 to 15 minutes, then soak in or rinse with dechlorinated tap water.

Household Bleach

If potassium permanganate is not available, you can make a comparably effective solution with household bleach.  Bleach is much more concentrated than necessary, however, and needs to be diluted extensively.  Even when greatly diluted, bleach is corrosive to soft plant tissues like roots, rhizomes, and some bulbs.  Stem plants are particularly sensitive, and in my experience it is not unusual for a stem plant to lose all its leaves after being submerged in even a weak solution.  In most cases the stem plants revive themselves after a couple of days, and the new growth adds bonus greenery.  Speaking plainly, potassium permanganate is a better choice, but bleach will suffice if necessary.

Many aquarists experienced in cleaning plants with bleach quote a dilution of 1 part bleach to 19 parts tap water.  A quick dip and swish is enough to remove any unwanted passengers.  However, I find even this strong for delicate stem plants like Cabomba and Limnophila, and a dip is not as effective as a soak.  I usually like to add 25ml of bleach to 1L of water^*—that’s a 1:40 ratio.  This dilution is sufficiently weak to actually soak the plants for 2 minutes, but it’s still advisable to keep the roots, rhizome, and bulb propped out of the solution.  After the soak, give the softer plant parts a quick dip, then promptly rinse all the plants (and their parts) in a tray of dechlorinated water.

^*A tablespoon and a half of bleach to a quart of water for you Imperial Folk.  J

Part III:  Finishing Touches

While your plants are having a dechlorination bath, it’s a good idea to sift through them all one at a time and inspect them for injuries.  Plants, like any living tissue, have a tendency to bruise when injured and will try to repair any damaged tissue.  However, plants are much healthier and more attractive when they are encouraged to produce new growth.  Now is the perfect time to start them on the road to lush green leaves!  Carefully clip off and remove any damaged leaves at the stem, or browning roots at the crown, and look for any extra debris that can be removed by hand.  Get to know the plants better, but keep them moist at all times to prevent the cells from drying out.

By now you may have also made some decisions about where to place your new plants in your aquascape.  Happy planting!

Summary

Disinfecting new plants is extremely important in keeping an aquarium disease- and parasite-free.  Even retail-store plants can carry snail eggs, diseases, parasites and Hydra.  Plants can be disinfected quickly and easily, most notably with potassium permanganate or a mild bleach solution.  When using bleach be attentive to roots and other soft porous parts, as they are easily corroded.

Soaking the plants is a great time to get to know them better.  Look for any stressed or damaged areas, and remove injured plant parts to encourage new growth.  Finally, plant and enjoy your new flora.

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