Overview & Origin
Red Root Floaters (Phyllanthus fluitans) originate from South America, where they float on the surface of slow-moving rivers, streams, and floodplains. The plant belongs to the family Phyllanthaceae and is the most popular colored floating plant in the aquarium hobby.
The plant's signature feature is its ability to change color based on light intensity. Under low to moderate light, leaves remain green with red roots. Under high light and good nutrition, the leaves transition to deep red, creating one of the most visually dramatic effects available in planted aquariums.
Basic Care
Red Root Floaters are simple to care for — simply place them on the water surface. No planting, no attachment, no substrate needed. Key considerations:
- Surface agitation: Minimal surface movement is preferred. Strong filtration outflow or air stones that disturb the surface can push floaters around, submerge leaves, and stress the plants. Use a spray bar aimed downward, or baffle filter outflow.
- Condensation: If using a glass lid, ensure there's a small gap for airflow. Water droplets falling from the lid onto the leaves can cause rot. Some aquarists leave a slight gap or use mesh lids.
- Containment: Use airline tubing or floating feeding rings to corral Red Root Floaters in one area if they're taking over too much surface area.
How to Get Red Coloration
The red coloration is the main attraction, and achieving it requires:
- High light: The #1 factor. Red Root Floaters sitting directly under a strong LED light will turn red. Those in shaded areas or under weak lights stay green. 50+ PAR at the surface is ideal.
- Iron supplementation: Iron is critical for red pigmentation. Dose Seachem Flourish Iron or a comprehensive fertilizer with iron 2–3 times per week.
- Low nitrogen: Some hobbyists report that lower nitrate levels (under 10 ppm) encourage red coloration, as the plant produces anthocyanins (red pigments) as a stress response to nitrogen limitation. This is debated but worth experimenting with.
Water Parameters
- Temperature: 70–82°F (21–28°C)
- pH: 6.5–7.5
- KH: 0–6 dKH (prefers soft water)
- GH: 2–8 dGH
Red Root Floaters prefer soft, slightly acidic water. They can struggle in very hard, alkaline water — if your tap water is hard, this may limit the intensity of red coloration achievable.
Maintenance
Under good conditions, Red Root Floaters multiply rapidly and can cover the entire water surface within weeks. Regular maintenance is essential:
- Thinning: Remove excess plants weekly. If the surface coverage exceeds 50–60% of the tank, light to submerged plants below will be significantly reduced.
- Dead leaf removal: Remove brown or rotting leaves and stems promptly to prevent water quality issues.
- Feeding: As floating plants, they access atmospheric CO2 and have no need for CO2 injection. Liquid fertilizer (especially iron) dosed into the water column keeps them thriving.
Common Problems & Solutions
- Leaves staying green: Insufficient light is the most common cause. Move directly under the brightest part of your light. Also supplement iron.
- Leaf rot/melting: Usually caused by water droplets from condensation landing on leaves, or leaves being pushed underwater by water flow. Reduce surface agitation and ensure proper lid ventilation.
- Slow growth: May indicate nutrient deficiency. Dose comprehensive liquid fertilizer. Hard, alkaline water can also slow growth.
- Roots not red: Root color correlates with overall health and light. Healthy plants under good light naturally produce red roots.
Frequently Asked Questions
Why won't my Red Root Floaters turn red?
The most likely reason is insufficient light. They need to be directly under high-intensity lighting. Additionally, supplement with iron and try slightly reducing nitrogen levels.
Do Red Root Floaters need CO2?
No — floating plants access CO2 directly from the atmosphere, which is approximately 400 ppm (far more than any aquarium). CO2 injection has no effect on floating plants.
Can I keep Red Root Floaters with a filter?
Yes, but minimize surface agitation. Point the filter outflow downward or use a spray bar. Strong surface currents push floaters around and can submerse leaves.