Choosing aquarium lighting for a planted tank vs a fish-only tank

The short answer: a fish-only tank needs only enough light to see your fish and keep a natural day-night rhythm, so almost any basic LED works and you should run it on a timer for six to eight hours a day. A planted tank is different. Live plants need a light with enough intensity and the right spectrum to drive photosynthesis, which means a purpose-built plant LED, not the dim strip that came with a starter kit. Getting this wrong is the most common reason a beginner's plants slowly melt away.

Fish-only tanks: keep it simple

If you are not growing live plants, light is for viewing and for the fish's comfort, not for growth. A standard LED fixture is plenty. The main mistake is leaving it on too long, which fuels algae. Put it on a timer, aim for six to eight hours a day, and keep the tank out of direct sunlight from a window, which in a bright Alberta room can turn water green quickly.

Planted tanks: intensity and spectrum

Plants care about two things from a light: how much usable light reaches them (intensity, which falls off quickly with tank depth) and the colour of that light (spectrum). A dedicated plant light such as the Fluval Plant Spectrum LED is built to deliver both. Basic fish lights usually cannot grow anything more demanding than a low-light plant.

Match the light to your plants. Low-light plants like anubias, java fern and cryptocoryne will grow under modest lighting. Carpeting plants and red stem plants want high intensity and, often, added carbon. Browse what will actually thrive in our live plants collection, and see the full range of fixtures in lighting and canopies.

More light is not better

Turning a strong plant light up to full for ten hours a day is the fastest route to an algae problem, especially before your plants are established. Start at a moderate intensity and a shorter photoperiod, then increase slowly only if the plants are growing and algae is not. A timer is your best friend here.

A note on marine tanks

Reef tanks are a separate world again: corals need high-output lighting in the blue spectrum, like the Fluval Marine Nano LED. A freshwater plant light will not keep corals alive, and a reef light is overkill for a community tank.

Related guides

• Live aquarium plants for beginners that actually survive
• Beating algae: identify it, then fix the cause

Come and ask us

Fishkeeping goes better when a real person can look at your setup. Come into the store in Lethbridge, call us at 403-380-4506, or send us an email, and someone who keeps fish will help you get it right. Written by the team at Tropical Fish Imports.