Dec 04, 2025

A Beginner's Guide to Aquarium Light Intensity: How to Choose the Right Lighting

When setting up an aquarium, one of the most important decisions you'll make is choosing the right lighting. It’s not just about having the prettiest lights – the intensity of your aquarium lighting can have a big impact on the health and well-being of your fish and plants. If you're a beginner, don't worry! This guide will break it down in simple terms so you can make the best lighting choice for your tank.

What Is Aquarium Light Intensity, and Why Does It Matter?

Aquarium light intensity refers to how strong the light is in your tank. It’s a key factor because fish, plants, and even beneficial bacteria rely on light to thrive. Plants, for example, use light for photosynthesis – the process that helps them grow and stay healthy. Fish, on the other hand, need a balanced light cycle to maintain their natural behaviour and sleep patterns.

Having the right light intensity ensures your aquarium ecosystem is balanced. Too little light can cause plants to wither and fish to feel stressed, while too much light can lead to algae blooms, which are a nightmare for any tank owner.

How to Choose the Right Lighting for Your Aquarium

Choosing the right light intensity can feel overwhelming, but it doesn’t need to be. Here are some simple tips to help you get it right.

1. Know Your Tank’s Needs

First, think about what you have in your aquarium. Is it a fish-only tank, or do you have plants? Fish-only tanks usually require lower light intensity, while planted tanks need more intense lighting to encourage plant growth.

Fish-Only Tanks: These tanks usually don’t require high light intensity. A basic LED light with a lower intensity setting should work just fine.
Planted Tanks: If you’re growing plants, you’ll need stronger lighting. Plants need light to thrive, and different types of plants require varying light intensities. Low-light plants, like Java Ferns or Anubias, do well with moderate light, while high-light plants, such as Amazon Sword or Rotala, need more intense lighting.

2. Understand the Light Levels

Light intensity is typically measured in lumens or PAR (photosynthetically active radiation), but don’t get bogged down by these terms. Here’s a simple guide to help you choose based on light levels:

Low Light: Around 10-20 PAR. This is great for plants that don’t require much light. You can get away with a lower wattage light for these types of plants.
Medium Light: 20-30 PAR. This is ideal for most aquarium plants and can be achieved with a slightly stronger light.
High Light: Above 30 PAR. High-light plants need more intense lighting, and you’ll want to make sure your aquarium has the right equipment to handle this level.

3. Duration of Light Exposure

It’s not just about how bright your light is, but also how long you leave it on. Fish and plants need a consistent light cycle to stay healthy. Most aquariums do well with around 8-12 hours of light each day. Too much light can stress your plants and fish, and too little can stunt plant growth and leave fish feeling unsettled.

4. Use the Right Fixtures

LED lights are a great choice for aquarium lighting because they’re energy-efficient, long-lasting, and can be adjusted for intensity. Many modern LED fixtures come with adjustable settings, so you can control the light intensity and duration easily. For a planted aquarium, you might want to invest in a good quality LED light that allows you to fine-tune the intensity to meet your plants' needs.

Scenarios: When Different Light Intensities Work Best

Low Light: If you're keeping fish like Betta fish or goldfish with some low-maintenance plants, low-intensity lighting is perfect. It’ll create a peaceful environment without encouraging algae growth.
Medium Light: For a mixed tank with fish and some easy-to-grow plants (like Java Moss or Anubias), medium-intensity lighting will help your plants flourish without overwhelming them.
High Light: If you're growing more demanding plants like high-light aquatic plants (e.g., Monte Carlo or Glossostigma), then a high-intensity light is essential. These plants thrive in brighter conditions and will need strong light to stay healthy.

Conclusion: Finding the Right Balance for Your Aquarium

Choosing the right aquarium lighting might seem complicated, but with a bit of understanding, it becomes easy. Start by considering the needs of your fish and plants, then choose a light intensity that suits your aquarium setup. Don’t forget to maintain the right duration of light exposure, and always check your light fixtures to make sure they’re up to the task.

Remember, every aquarium is unique, and it might take a little experimentation to get it just right. If you’re unsure, don’t hesitate to check out more tips or products at School of Scape, where they provide expert advice to help beginners create their perfect aquascape.