Aquarium Lights: LED, Planted-Tank and Timer Setups Compared

An aquarium light is for viewing, for keeping a steady day and night, and, in planted tanks, for plant growth. The RSPCA suggests 8 to 10 hours of light a day, and RSPCA Australia at least 8 hours of darkness, so a timer is the simplest fix. Keep the tank out of direct sunlight, as VCA advises.

What an aquarium light is for

A light does three jobs, and each asks something different of it:

For a fish-only tank with artificial plants, a basic LED strip or the light in a kit’s lid is enough. The Marina LED kits, for example, build the light into the canopy. Planted tanks need more.

Aquarium LED lights and planted-tank fixtures

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How many hours of light?

The RSPCA suggests 8 to 10 hours of light a day on an artificial cycle, and says to avoid placing the tank by a window. RSPCA Australia’s goldfish guidance sets a maximum of 10 hours of light with at least 8 hours of darkness.

Those numbers sit comfortably together: pick a fixed block such as 10 in the morning to 8 at night. Aqueon suggests putting the light on a timer so the cycle stays consistent, which also means the light is off when you are away.

Why sunlight is a problem

VCA says a tank should be shielded from direct sunlight. The RSPCA gives the same advice and prefers an artificial light cycle. Sun through a window adds light you cannot switch off and can warm the water, which unsettles the temperature your heater is holding.

Fixing too much light starts with the timer and the tank’s position, before any cleaning. The cleaning chapter covers algae scrapers for the glass.

Planted-tank lights and PAR

Plants use light between 400 and 700 nanometers for photosynthesis, the range called photosynthetically active radiation, or PAR, as the Science Learning Hub defines it. Light for viewing only needs to look good; light for plants needs enough PAR to reach the substrate.

When you compare planted-tank lights:

• Look for the maker’s published PAR figure at a stated depth, and compare it with your tank’s height.
• Check that the fixture covers the tank’s full length; a short light leaves dim ends.
• Prefer a light with a built-in timer or one you can put on an outlet timer.

Live plants are sold by aquarium retailers, with care notes that describe the light each plant needs; we describe them but do not link them. Artificial silk plants need no special light. The substrate and decor chapter covers aqua soils for planted tanks.

Silk plants and decor that need no special light

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A sample schedule on a timer

Here is one way to meet both RSPCA pages with an outlet timer. Shift the times to suit when you are home to watch the tank.

A timer also helps on days you are away: the fish keep the same day and night, which is the consistency Aqueon’s setup guide asks for. If you use a heater and light on the same power strip, give each cord its own drip loop.

Kit lights or a separate fixture?

Some starter kits build the light into the lid. The Marina LED kits, for example, integrate the LED strip into the canopy, powered through a transformer with an on and off switch on the cord, and the manual says to use only the supplied transformer. That is enough for fish and artificial plants.

A separate fixture makes sense when you add live plants, when the lid light does not reach the whole tank, or when you want a built-in timer. Measure the tank’s length before you buy, and check whether the fixture sits on the rim, hangs above it or clips on, as the small nano lights do.

Safety and placement

Light fixtures sit just above the water, so the same rules apply as for heaters and filters. The Marina kit manual says to make a drip loop in the light’s cord, to unplug the light before cleaning it, and to make sure every surface is dry before reconnecting it. For cleaning, it suggests wiping exposed surfaces with a damp cloth to remove dust and mineral deposits, handling the unit with both hands.

Place the tank where you can see it but the sun cannot reach it. For heating, see aquarium heaters, and for the full list of gear, the setup checklist.