Certain aquarium enthusiasts use pothos plants with their roots submerged to help manage nitrate levels between water changes. Using pothos to lower nitrates in aquarium setups is a popular and natural method that can reduce the need for frequent water changes. This approach leverages the plant’s fast-growing roots to absorb excess nutrients directly from the water column.
It’s a simple, low-cost solution that many fish keepers swear by. This guide will explain exactly how it works, how to set it up correctly, and what you need to watch out for.
Pothos To Lower Nitrates In Aquarium
Pothos, scientifically known as Epipremnum aureum, is a common houseplant celebrated for its hardiness. In the aquarium context, it’s used emersed, meaning the leaves stay above water while the roots dangle in the tank. The plant acts as a powerful nutrient sponge, with its roots actively uptaking ammonia, nitrite, and nitrate as fertilizer for growth.
This process directly competes with algae for resources and can lead to clearer water and healthier fish. It’s not a complete replacement for filtration or water changes, but it is an excellent supplemental filtration method.
How Pothos Lowers Nitrate Levels
Nitrate is the final product of the nitrogen cycle in your tank. While less toxic than ammonia or nitrite, high nitrate concentrations can stress fish, inhibit reproduction, and promote rampant algae growth. Pothos plants absorb these nitrogen compounds through their roots, using them to produce new leaves and stems.
Because pothos is a terrestrial plant with access to atmospheric CO2, it can grow very quickly compared to many fully aquatic plants. This rapid growth translates to a higher demand for nitrogen, making it an efficient nitrate remover. Essentially, you are exporting nutrients out of the aquarium water every time you trim a vine.
The Science Behind Nutrient Uptake
The roots of pothos are highly efficient at absorbing nutrients in a dissolved form. They take in ammonium/ammonia and nitrate ions directly, bypassing the need for the bacterial conversion that aquatic plants typically rely on. This direct uptake can provide a more immediate reduction in measurable nitrate levels between your regular maintenance schedule.
Benefits Beyond Nitrate Reduction
While nitrate control is the primary goal, adding pothos offers several other advantages for your aquarium ecosystem.
- Improved Water Clarity: By outcompeting microscopic algae for nutrients, pothos can help clear green water.
- Additional Surface Cover: The trailing vines provide shade and shelter for fish, which can reduce stress.
- Enhanced Aesthetics: It creates a beautiful, natural “green roof” effect above your tank.
- Oxygenation: Although minimal, the roots do release some oxygen into the water during photosynthesis.
- Cost-Effective Filtration: It’s an incredibly inexpensive way to boost your tank’s filtration capacity.
Choosing And Preparing Pothos For Your Aquarium
Not every pothos plant from a garden center is ready to go straight into your tank. Proper selection and preparation are crucial to avoid introducing contaminants and to ensure the plant thrives.
Selecting The Right Plant
Look for healthy, vibrant pothos vines. Golden pothos is the most common and effective variety. Avoid plants that show signs of disease, pests, or yellowing leaves. If possible, source a cutting from an existing aquarium setup, as it will already be adapted to aquatic roots.
Important Safety Precautions
Pothos is toxic if ingested by cats, dogs, or humans. The leaves contain calcium oxalate crystals. Always wash your hands after handling the plant, and ensure it is placed where pets cannot chew on the vines. The toxicity is not a concern for fish, as they do not eat the plant.
Step-By-Step Preparation Process
You must properly clean and transition the plant to avoid harming your aquarium’s inhabitants.
- Take Cuttings: Use clean scissors to cut a stem section 6-10 inches long, ensuring it has at least 4-5 leaves and several nodes (the little bumps on the stem).
- Remove Lower Leaves: Gently pull off the leaves that would be submerged. Roots will emerge from the nodes where leaves were attached.
- Rinse Thoroughly: Rinse the entire cutting under cool, running tap water to remove any soil, pesticides, or potential pests.
- Optional Disinfection: For extra caution, soak the cutting in a mild bleach solution (1 part household bleach to 19 parts water) for 2-3 minutes, then rinse it thoroughly with dechlorinated water.
- Root in Water (Optional): You can pre-root the cutting in a separate container of dechlorinated water for a few weeks until roots are a few inches long before adding it to the tank. This can speed up the process.
Installation Methods And Setup Guide
There are several effective ways to secure pothos in your aquarium. The key is to keep the leaves completely out of the water and the stems and nodes submerged.
Hanging The Pothos From The Back
This is the most common and straightfoward method. You simply suspend the plant so the roots dangle into the water from the top rear edge of the tank.
- Use suction cups with clips attached to the tank’s rim.
- Utilize the gap between a hang-on-back filter and the aquarium glass.
- Rest the stems across a stable light fixture or tank hood.
Using A Floating Plant Holder Or Raft
A floating ring or raft, often used for terrestrial plants in ponds, can corral the pothos at the water’s surface. This is a good option for open-top aquariums and allows for easy repositioning.
Planting In The Filter
For hang-on-back or canister filters with a media basket, you can place pothos cuttings directly into the filter compartment. The constant water flow provides excellent nutrient access and hides the roots from view. Ensure the leaves are outside the filter box to recieve light.
Step-By-Step Installation
- Ensure your tank lid or light has enough space for the plant’s leaves.
- Choose your mounting method (suction cup, filter, etc.) and have it ready.
- Place the prepared pothos cutting so that only the bare stem and nodes are underwater. All leaves must be in the air.
- Secure the stem to prevent it from falling completely into the tank.
- Arrange the vines so they recieve adequate indirect or artificial light.
Care And Maintenance For Aquarium Pothos
For pothos to effectively lower nitrates, it needs to be healthy and growing. Proper care is simple but essential.
Lighting Requirements
Pothos is very adaptable. It will grow under standard aquarium lighting if the leaves are above the water. It also thrives in normal room indirect sunlight. Avoid placing it in direct, harsh sunlight, which can scorch the leaves.
Nutrient Supplementation
In a heavily stocked tank, the fish waste may provide all the nutrients the pothos needs. However, in lightly stocked or planted tanks, the pothos might consume all available nitrates and then show signs of deficiency, like yellowing leaves. If this happens, you can occasionally add a liquid fertilizer formulated for houseplants to the water, but do so sparingly to avoid fueling algae.
Managing Leaf Yellowing
If older leaves turn yellow, it’s often a sign of nitrogen deficiency—meaning the pothos is doing its job well. Simply snip off the yellow leaves. If new growth is yellow, it may need a broader range of nutrients; a comprehensive liquid fertalizer can help.
Pruning And Growth Management
Regular pruning encourages bushier growth and more root mass, which increases nitrate uptake. When vines get too long, cut them back to a node. You can replant these cuttings to create more pothos stations in the same or other tanks. Pruning is the primary way you “export” nitrates from the system.
Root Maintenance
The roots will grow long and thick. You can trim them back during water changes if they become too dense or start clogging filter intakes. Use clean scissors and trim no more than one-third of the root mass at a time to avoid shocking the plant.
Potential Drawbacks And Considerations
While beneficial, using pothos is not without its potential issues. Being aware of them helps you manage the system effectively.
Allelopathy And Plant Compatibility
Some reports suggest pothos may release allelopathic chemicals that can inhibit the growth of certain other plants, like floating plants or slow-growing aquatic species. Monitor your other plants for stunted growth. It’s generally safe with most common aquarium plants, but its something to watch.
Competition With Other Plants
Pothos is a nutrient powerhouse. It can outcompete submerged aquatic plants for nutrients like nitrate, potassium, and iron. If you have a dedicated planted aquarium, you may need to increase fertilization to support all the plants.
Risk Of Rot And Water Quality Issues
If a stem or leaf is submerged and begins to decay, it will pollute the water. Always remove any submerged leaves immediately. Ensure the transition point between stem and leaf is above the waterline.
Limited Impact In Heavily Stocked Tanks
Pothos is a supplement, not a miracle cure. In a severely overstocked tank producing vast amounts of nitrate, pothos alone cannot keep up. It works best as part of a balanced maintenance routine that includes proper feeding, adequate filtration, and regular partial water changes.
Monitoring Your Success
How do you know if your pothos is actually working? The proof is in the testing and observation.
Testing Nitrate Levels
Use a reliable liquid nitrate test kit (not test strips for accuracy). Test your water weekly. After introducing healthy pothos, you should observe a measurable decrease in the rate of nitrate accumulation between water changes. For example, if nitrates rose 20 ppm per week before, they might only rise 10 ppm per week with pothos.
Observing Plant Growth
Vigorous growth of new leaves and roots is the best visual indicator that the plant is actively consuming nutrients. If the plant is stagnant, it’s not lowering nitrates effectively. Check its light and consider if it needs supplemental nutrients.
Balancing The Ecosystem
The goal is stability. You may find you can extend the time between water changes slightly, but never eliminate them entirely. Water changes replenish essential minerals and remove hormones and dissolved organics that pothos does not address. Use pothos to maintain lower nitrate levels, not as an excuse to neglect other tank duties.
Frequently Asked Questions
Is Pothos Safe For All Fish And Shrimp?
Yes, pothos is generally considered safe for all fish, shrimp, and snails. The roots provide excellent biofilm for shrimp to graze on. The concern is only for terrestrial pets that might eat the leaves.
How Long Does It Take For Pothos To Lower Nitrates?
You may see a small difference within a couple of weeks as roots establish. Significant nitrate reduction typically becomes apparent after 4-8 weeks, once the plant has developed a substantial root system and is growing vigorously.
Can I Use Other Houseplants To Reduce Aquarium Nitrates?
Yes. Several other semi-aquatic plants work similarly. Peace lily (Spathiphyllum), spider plant (Chlorophytum comosum), and philodendron are common alternatives. The same principles apply: only the roots should be submerged.
Why Are The Roots Of My Pothos Turning Brown?
Slight browning is normal as roots mature. However, slimy, mushy brown roots indicate rot, often due to lack of water flow or oxygen. Trim the rotten roots, and consider placing the plant in an area with better circulation, like near a filter outlet.
How Many Pothos Cuttings Do I Need For My Tank Size?
Start with 2-3 cuttings for a tank under 30 gallons. For larger tanks, you can use more. It’s easier to add more plants later than to manage an overgrown jungle from the start. The bioload of your fish is a bigger factor than tank volume alone.