How to Balance Aquarium Lighting to Grow Healthy Plants (and Avoid Algae)

A brand-new planted tank always looks so beautiful and pristine, but if the tank is unbalanced, those same plants may become sickly-looking and overrun with algae within a couple of months. Plants and algae both use the same resources— such as light, nutrients, and carbon dioxide — so the goal is to balance these resources so that the plants grow stronger and outcompete the algae. For instance, too much or too little light can cause algae growth, so we need to fine-tune it for optimal plant growth. In this article, let’s talk about how to balance the lighting so that it’s the right amount for your specific tank and plant selection.

Before we begin, remember that plants are living organisms, so it takes time for them to react to lighting changes and show visible signs of improvement. For low tech aquariums without CO₂ gas injection, we recommend making one adjustment at a time and waiting two weeks before making the next change. Otherwise, if you make multiple changes all at once, you have no idea what worked and what did not.

1. Location

For optimal control of the lighting, avoid placing your aquarium in direct sunlight. The sun may be more powerful than you need, especially if you are growing low light plants. Additionally, the fickle weather may be sunny one day and cloudy the next, and every season has different amounts of daylight. Yes, some experienced hobbyists can manage planted tanks that get sunlight, but for most of us, the fluctuating changes make it difficult to balance the aquarium because the plants are getting widely varying amounts of light every day.

2. Equipment

To create the ideal environment for growing an underwater garden, we recommend getting a light specifically designed for aquarium plants. The default lights that come with aquarium kits are often too dim, while cheap shop lights or other DIY solutions may not spread the light properly or have a color temperature that looks good. A planted tank light is optimized for growing aquarium plants, making your job easier. The best lights have the right brightness, good spread that won’t shine into your eyes, and a natural color spectrum that makes fish and plants look their finest.

Use a timer to create a regular schedule for the light to turn on and off each day.

3. Light Duration

Put your light on an electrical outlet timer so it turns on and turns off at the same time every day. Timers are much more reliable than people, so even if you get sick, go on vacation, or just plain forget, your plants will get the light they need. In a newly planted aquarium, we recommend starting with only 6–8 hours a day because the plants will need time to get used to their new surroundings. Once the plants get bigger and need more light to grow, slowly increase the lighting up to 8–12 hours a day. If algae starts getting out of control, then decrease the duration again. Some hobbyists like to split up the timing of the photo period with an “afternoon siesta” so it turns on in the morning while you’re eating breakfast, turns off while you’re at work or school, and turns on again at night when you’re back.

As a reminder, do not leave the light on all night, not even in blue moonlight mode. Every night, the plants must rest by entering the respiration cycle to consume oxygen and sugars. Even if you leave the light on 24/7, they will not photosynthesize during the respiration cycle, so algae will take advantage of the excess photons and take over your aquarium.

4. Light Intensity

Most planted tank lights nowadays are made with LED technology and are powerful enough to grow both low and high light plants. Depending on the plants you have chosen and the height of the tank, a light at 100% brightness may be too strong and cause algae to flourish. Start with a lower light intensity around 20–40% brightness and gradually increase the intensity if there is no algae growth. If a significant algae bloom occurs, then lower the brightness again. Also, if the light does not have a programmable dimness setting, then consider raising the light above the tank or blocking out some of the LEDs using black electrical tape.

Aquarium lighting with different brightness levels and color modes

5. Fine-Tuning

Even after you balance the light duration and intensity, remember that aquariums are ever-changing ecosystems and therefore may need further adjustments in the future. A newly planted tank needs less light since the plants are still small and growing. In contrast, mature tanks may have huge plants that shade out everything, so you may need to prune back the leaves or increase the lighting. Jotting down your light settings in an aquarium journal or spreadsheet over time can help with balancing planted tanks so you can see which values work the best.

What is the Best Light for Planted Aquariums?

When picking an aquarium light, there are many options on the market that range from relatively inexpensive to extremely steep. The key is to determine which features are most important to you and the type of planted tank you want to set up. Also, you want to pick a good quality brand that will last, rather than buying the cheapest option that has a very short warranty and LEDs that go bad after a few months.

Easy Plant LED

In our search for an affordable yet long-lasting light that makes plants look amazing, we ended up designing our own Easy Plant LED. It includes all our favorite features, such as:

• The 3-year warranty and lights rated for 50,000 hours of operation
• The high-quality, energy-efficient LEDs that bring out the stunning colors of fish and plants while reducing power usage by 10–50%
• The highly water-resistant IP67 rating so it won’t fail from accidentally dropping in water or getting splashed by an air stone
• The easy-to-use controller for changing between white Daylight and blue Moonlight modes
• The dimmable light settings that allow you to adjust the brightness from 10–100% to grow both high and low light plants
• The extra-long, 12-foot power cord so you reach even the furthest outlet in the room
• The extendable sliding brackets to make sure you get a snug fit and prevent light from bleeding out
• The thick aluminum frame to dissipate heat from the LEDs and prevent bowing in longer models

Our goal is to make the fishkeeping and planted tank hobby as easy as possible, which is why we created the Easy Plant LED as a dependable, all-purpose solution that produces excellent plant growth. This light, paired with our Easy Green and Easy Root Tab fertilizers, is our answer to making the ultimate Easy Planted Aquarium.