Filters & Heaters

Aquarium Lights: How Much Light, and LEDs Compared

Fluval Plant 3.0 LED aquarium light

TankAndFin is reader-supported. If you buy through our links we may earn a commission at no extra cost to you. As an Amazon Associate we earn from qualifying purchases. Disclosure.

Quick answerRun your light on a timer for about 12 hours a day, per Habitattitude, and don't leave it on constantly, which feeds algae. Planted tanks need at least 8 to 10 hours, per Purdue Extension. Lights with built-in timers, like hygger's 24/7 LEDs or the Fluval Plant 3.0, take care of the schedule for you.

Lighting is mostly about consistency. Here's what Habitattitude and Purdue Extension say, and lights that automate it. Product details are from the listings; we haven't tested them.

How much light

  • A steady cycle: Habitattitude: "a 12-hour light/dark cycle is healthy. Avoid constant lighting that promotes algae."
  • Plants: Purdue: a planted tank needs "at least 8 to 10 hours of light a day." It adds that Cryptocoryne "needs little light," while Vallisneria and Sagittaria "need lots of light."
  • Algae as a gauge: Purdue: "If algae grows fast, your tank is getting too much light. With too little light, algae won't grow at all but neither will the plants."
  • LEDs: Habitattitude says LEDs are energy-efficient, generate little heat and last 10,000 to 50,000 hours.

Lights compared

hygger 24/7 LEDs

A default mode cycles from orange sunrise to white daylight to blue moonlight, and a DIY mode sets time, brightness and color, per the listing. hygger's official sizing pairs wattage to tank length: for example, 14W for 12-18 in. and 18W for 18-24 in. tanks. (The 14W Amazon listing says 12-20 in.)

hygger 24/7 Clip-On LED (14W)
14W clip-on

hygger 24/7 Clip-On LED (14W)

  • For 12-20 in. tanks, per the listing
  • Sunrise, daylight and moonlight auto cycle
  • DIY timer: 6, 10 or 12 hours
Check price on Amazon
hygger 24/7 LED (18W)
18W, 18-24 in.

hygger 24/7 LED (18W)

  • For 18-24 in. tanks, per the listing
  • Sunrise, daylight and moonlight auto cycle
  • Extendable bracket
Check price on Amazon

Fluval Plant 3.0

Programmable 24-hour light cycle, full spectrum with six band waves, and preset habitat modes, per the listing. The 22W version fits 15-24 in. tanks.

Fluval Plant 3.0 LED (22W, 15-24 in.)
22W, 15-24 in.

Fluval Plant 3.0 LED (22W, 15-24 in.)

  • Programmable 24-hour light cycle, per the listing
  • Full spectrum, six band waves
  • Preset habitat modes; extendable brackets
Check price on Amazon

Kits with lights

The kits in our starter kit guide include LED lighting. Fluval's Flex 2.0 has RGB plus white LEDs with a remote; see Flex vs Spec.

FAQ

How long on?

About 12 hours; planted tanks at least 8-10.

Algae?

Often too much light, per Purdue.

LED heat?

Little, per Habitattitude.

Sources

  1. Habitattitude: Tanks, equipment, maintenance
  2. Purdue Extension: Planting your aquarium (HO-24)
  3. hygger: Auto on/off LED (HG999)