Pothos (Epipremnum aureum) is a common houseplant popular among aquarium hobbyists for its dual benefits. This hardy vine adds a lush, natural aesthetic when its roots drape into the water. Beyond decoration, Pothos functions as a powerful, natural water filter. The plant efficiently absorbs excess compounds, particularly nitrates, which are the final product of the aquarium’s nitrogen cycle. Utilizing Pothos significantly improves water quality and reduces the frequency of required water changes.
Selecting and Preparing Cuttings
Start by selecting a healthy section of the parent plant for successful growth. Look for a stem with several leaves and identify the nodes, which appear as small bumps or aerial roots along the vine. Use clean scissors or shears to make the cut about a quarter-inch below a node, as this is the point where new water roots will sprout.
Use only cuttings, not entire potted plants, to prevent introducing soil into the aquarium. Terrestrial soil contains fertilizers and organic matter that can cause ammonia spikes and algae blooms. Thoroughly rinse the cutting under running room-temperature water to remove residual dirt, pests, or chemical treatments like pesticides. This cleaning step protects the aquarium’s ecosystem and the health of the fish.
Safe Submersion Techniques
Only the nodes and emerging roots of the Pothos cutting should be submerged in the aquarium water to prevent the plant from rotting. The leaves and the majority of the stem must remain dry and above the water line. Submerged foliage will decompose and release harmful waste back into the tank. Keeping the leaves dry allows the plant access to atmospheric carbon dioxide, which fuels rapid growth and high nutrient absorption.
There are several methods for securing cuttings to the tank rim or lid while keeping the leaves dry. These include using specialized plastic clips designed to hold stems against the glass edge or employing suction cups with small rings. A highly effective method is placing the cutting directly into the outflow section of a hang-on-back (HOB) filter. The constant flow of nutrient-rich water over the roots maximizes the plant’s ability to pull nitrates from the system, working as an efficient biological reactor.
Long-Term Care and Toxicity Considerations
For continued health and maximum nitrate absorption, Pothos requires moderate, indirect light outside the aquarium. While Pothos can tolerate low light, providing bright, indirect sunlight or supplemental light from an elevated aquarium fixture will significantly increase its growth rate and effectiveness as a natural filter. As the plant establishes itself, its roots will grow long and dense, requiring occasional trimming outside the tank to prevent interference with fish movement.
The plant is highly effective at absorbing nitrates, sometimes reducing the need for water changes dramatically. However, the water still needs to be replenished for essential minerals and to correct pH shifts. A primary consideration is the plant’s toxicity; Pothos contains calcium oxalate crystals in all its tissues. When ingested, these crystals can cause irritation and swelling in mammals, including household pets like cats and dogs.
The risk to fish is minimal because the crystals are largely insoluble in water with a pH above 4.5, which covers the range of most home aquariums. Leaves must be kept out of the water to prevent decomposition. Caution is advised in homes where pets or small children might chew on the vines hanging outside the tank.