The short answer
Most aquarium plants need 6–8 hours of moderate light per day on a timer. The easy species thrive on low-to-moderate light. Crucially, more light without more CO2 and fertilizer grows algae, not plants — light drives demand, and if nutrients or carbon can’t keep up, algae take the surplus.
It’s a balance, not a race
Think of light, CO2, and nutrients as three legs of a stool. Light sets how fast plants want to grow; CO2 and ferts determine whether they can. Push light far ahead of the other two and you create an imbalance that algae exploit. That’s why turning the light up rarely fixes struggling plants — and often makes algae worse.
- Low-tech (no CO2): keep light modest and rely on easy plants. See the easiest beginner plants.
- High-tech (with CO2): you can run brighter light, but only alongside injected CO2 and a full fertilizer routine.
Getting your light right
- Use a timer for a consistent daily photoperiod — start at 6–7 hours and adjust.
- Match intensity to your goal: carpeting and red plants demand strong light plus CO2; anubias, java fern and crypts are happy with much less.
- Choose the right fixture: see the lighting hub and our best light for a planted tank, or a wallet-friendly budget light.
If algae appears
Algae despite “correct” light usually means the light is outrunning CO2 or nutrients, or the photoperiod is too long. Trim the hours first, then rebalance. For a full plan, read how to get rid of aquarium algae, and if you’re adding CO2, start with CO2 for beginners.