LIGHTING & CO₂

LED Aquarium Light

Dimmable multi-channel LED fixture; spectrum and PAR matter far more than wattage.

Planting stage Lighting

Unplug before servicingHands out of the water firstDrip loop on every cableTest before you dose30 ppm CO₂ ceilingCycle before stocking

Lighting

Technical line drawing of LED Aquarium Light

Specification
Power	10–120 W
Channels	White / red / blue, independently dimmable
Colour temperature	6500–10000 K
PAR at 30 cm	60–250 µmol/m²/s
Control	Manual, timer or app
Mounting	Riser legs or suspended

Technical parameters
Low light	20–40 µmol/m²/s at substrate
Medium light	40–80 µmol/m²/s
High light	80–150+ µmol/m²/s
Photoperiod, new tank	6 h at 50%
Photoperiod, mature	7–8 h at full
Ramp duration	15–30 min

Modern planted-tank lighting is LED, and the useful specification is not wattage but PAR — photosynthetically active radiation, the light in the 400–700 nm band that chlorophyll can actually use — measured at the substrate in µmol/m²/s.

A fixture with separate white, red and blue channels lets you tune both intensity and spectrum. Red around 660 nm and blue around 450 nm drive photosynthesis hardest; green is largely reflected, which is why plants look green and why a green-heavy spectrum looks bright to you but grows plants poorly. Most quality fixtures run a white channel for appearance plus red and blue for growth.

The practical control is a dimmer and a schedule. Starting a new tank at 6 hours and 50% intensity, then extending by 30 minutes a week to a maximum of 8 hours, prevents the algae bloom that follows a full-intensity start on an immature tank. A ramp-up and ramp-down also stops fish being startled and is closer to what happens in the wild.

Safety and welfare

Keep the fixture and its power supply well clear of the water surface and splash. Aquarium lights are not submersible unless stated.
Use a drip loop on the cable. Water running down a light cable into a socket is a real and common failure.
Do not look directly into high-output LEDs at close range — the blue peak is intense and uncomfortable.

Using it well

Judge light by the plants, not the box. If lower leaves drop and algae grows on the glass, intensity is too high for the CO₂ and nutrient supply.

Aim for a single uninterrupted photoperiod. A siesta in the middle reduces total photosynthesis and does not help algae control.

Raise the fixture rather than dimming it if you want a wider spread. Dimming changes intensity; height changes both intensity and coverage.

Suits

Monte Carlo carpetAnubiasJava fernDutch styleIwagumiLow-tech tanks at reduced intensity

Note. Parameters are conventional ranges across the category, not the claim of any one manufacturer. Nothing on this page is for sale and no outcome for any plant or animal is guaranteed. Simulator output elsewhere on this site is a simplified model, not a measurement — confirm everything with a test kit and the equipment's own instructions.

LED Aquarium Light

Using it well

Suits

Works alongside