How much light does Common Duckweed need?

Medium light, around 30–60 µmol·m⁻²·s⁻¹ of PAR. Watts are not comparable between fixtures; PAR is. If the manufacturer does not publish PAR, pick one band lower than the tank depth suggests.

Does Common Duckweed need CO₂?

No. Marked "not needed": it grows normally in a tank with no CO₂ at all. These are usually slow growers that are also forgiving about light.

What water does Common Duckweed want?

15–30 °C, pH 6–8, 2–15 dGH. At 13 dGH wide it is one of the more forgiving ranges.

How fast does Common Duckweed grow, and where does it go?

Growth rate: fast. Placement: floating. Substrate: no substrate needed. Difficulty: beginner.

G-02 / 21Freshwater

Common Duckweed浮萍

Lemna minor · Lemnaceae

It doubles every two or three days and strips nitrate, and it can just as easily smother the surface.

Illustration to come

G-02 / 21 · Common Duckweed Lemna minor

SpecificationsPlant atlas

Name: 浮萍
Scientific name: Lemna minor
Family: Lemnaceae
Origin: Ponds, paddy fields and ditches worldwide
Light: Medium light
PAR: 30–60
CO₂: Not needed
Hardness: 2–15 dGH
Growth: Fast
Placement: Floating
Substrate: No substrate needed
Level: Beginner

Water requirementsFreshwater

Temp.15–30 °C

pH6–8

Hardness2–15 dGH

Alkalinity1–10 dKH

Units: temperature in °C, hardness in German degrees (dGH / dKH), marine salinity as specific gravity at 25 °C, volume in litres. These are the values recorded for the species and do not follow the site unit switcher.

Growing notes

1It multiplies fast, doubling in two or three days when conditions suit, so remove at least half every week.
2Keep it under a third of the surface, because too much shade stalls and yellows the plants below.
3It is an effective nitrate consumer, and a small patch visibly lowers nitrate in a new or over-fed tank.
4It grows tidiest in still water; pushed under by flow, it whitens and dies.
5Never tip it into a drain or pond; dry it out and compost it.

Frequently asked questions

How much light does Common Duckweed need?: Medium light, around 30–60 µmol·m⁻²·s⁻¹ of PAR. Watts are not comparable between fixtures; PAR is. If the manufacturer does not publish PAR, pick one band lower than the tank depth suggests.
Does Common Duckweed need CO₂?: No. Marked "not needed": it grows normally in a tank with no CO₂ at all. These are usually slow growers that are also forgiving about light.
What water does Common Duckweed want?: 15–30 °C, pH 6–8, 2–15 dGH. At 13 dGH wide it is one of the more forgiving ranges.
How fast does Common Duckweed grow, and where does it go?: Growth rate: fast. Placement: floating. Substrate: no substrate needed. Difficulty: beginner.