Aquarium Lighting Calculator – Why Is It Important Factor?

We all know that plants in general as well as aquatic plants in particular need light for photosynthesis. During this process, aquatic plants rely on light to absorb necessary substances, and CO2 releases O2 (plants breathe). And vice versa, when the lights are off, the tree takes in O2 and releases CO2.

Both processes balance each other to help the tree survive and grow. Light is the lifeblood of an aquarium. Lighting for the aquarium is one of the important issues that need attention.

Through the process of studying light, we have collected a little knowledge and experience that we want to share with you in the article Aquarium Lighting Calculator. Stay tuned to learn more about how to calculate light for your aquarium.

The importance of lighting in an aquarium

Light is one of the three important factors that form a complete aquarium (light, nutrients, CO2). But what light and how much light is enough depends on many other factors.

The importance of lighting in an aquarium

Choosing the right lights for the aquarium not only helps plants grow healthy, but it also determines whether the care and maintenance of the tank will be simple in the future. The most typical example is that inappropriate lighting will encourage the growth of harmful mosses, making tank cleaning complicated.

In a tank with low light, plants will shrivel, and grow slowly no matter how much nutrients and CO2 are invested. When there is too much light, ie nutrients and CO2 are low, or too few plants or only plants with little light, the moss will break out violently, sometimes irretrievably, uncontrollably.

Read more: Lumen Calculator – How do calculate the lumens of LED lights?

How do plants absorb light?

White light is a beam of light consisting of all 7 colors in nature. Just like in nature, plants will grow and develop well if the light is in the white light area or the light has a color temperature of 5400K to 12000K (K: kelvin – is a unit of measurement for the color temperature of light).

As for the red-leaved plants, they will grow quickly and have beautiful colors with shadows from 4500K to 6500K. For green leafy plants, they will be green if we use light from 9500K to 12000K.

The color of the landscape around us in natural conditions is projected by the full spectrum frequencies from the sun, unaffected by light color temperature. In contrast, in aquariums under artificial light with crevices in the interference of the spectrum, we sometimes see plants and fish as logs (under HQL light, for example).

Many aquatic plants require strong light even though only a small part of the light is absorbed during photosynthesis. The blue and red regions of the spectrum are most useful.

Time to provide light for the aquarium

Most natural environments have around 12 hours of light per day. Aquatic plants need to receive regular light for a certain time. The best way is to use a device that supports automatic on and off timers for 8-12 hours/day.

With a tank with many bulbs, you should also apply the method of gradually reducing the light by gradually turning off the lights for 5-15 minutes so that the aquatic plants and fish are not shocked by the sudden change.

Aquatic plants also need time without light ie turning off the lights completely. During this time, the plant stops photosynthesis and begins to breathe, so the light-off phase is a “rest” period for the plant’s biological functions.

Time to provide light for the aquarium

#1. Apply lunch break for aquariums

Plants can maintain their level of photosynthesis with relative ease and respond quickly to any variation in lighting conditions. In other words, they don’t take long to warm up and begin photosynthesis once fully illuminated.

However, algae do not have the biological advantage of aquatic plants and require long and relatively constant light periods to grow effectively. Algae can be eliminated from the aquarium by controlling the intensity and duration of light and applying a “lunch break”. This is the phase of turning off the lights in the middle of the aquarium’s normal day/night cycle.

If the aquarium is lit for 5-6 hours, then rests for 2-3 hours, and then lights again for another 5-6 hours, the plant will not be affected and will still receive enough light for a whole day. But the level of algae growth will be significantly reduced and even begin to slowly die off. This is an effective method of killing moss for aquariums with light.

#2. Reduce aquarium light loss

There are many causes of poor light quality in an aquarium. For example, dirty lake water, residue clinging to leaves, and tube light bulbs after 6 months also reduce their lifespan and get dusty over time. Therefore, taking care of the aquarium and adjusting the light to a stable level will help the aquarium develop the best.

Read more: How to Convert Lumen to Watts – Lumen Watt Conversion Calculator

Calculate aquarium lighting

The amount of light for aquariums, applied in most aquariums is 0.5watt/liter. For LEDs, watt/lit cannot be applied. At this time, it is necessary to use Lumen/liter to be more accurate. 20 lumens/liter of water would equate to about 0.5watts/liter for a fluorescent lamp.

#1. The traditional way of calculating the amount of light – in watt/liter lake

The traditional way of calculating the amount of light – in watt_liter lake

Watt: traditional calculation, watt/liter tank. The amount of light just enough for aquatic plants to grow is 0.5w/l. While this is the traditional way of calculating light output, this is for t8 bulbs.

So, for a 60/40/40 tank with a volume of 96 liters, one idea 60 troughs with a capacity of 54w is enough. It might sound a little ridiculous, but it’s a necessity. Of course, the more lights, the faster the plant will grow and the better color it will be. But more lights have to provide more nutrition, CO2, and more maintenance to clean the lake, moss is also easier to break out.

Lumen: For LED, we cannot apply watt/liter, but must use lumen/liter. Usually, 20lumen / 1 liter of water will be equivalent to 0.5 watts/liter for fluorescent lamps.

However, when using the lumen or watt/liter calculation method, there are also many shortcomings. For example, you use 300 watt t5 for a 300-liter lake, but if your lake has a depth of up to 80 90 cm, the amount of light on the background will be very weak, or if you hang the light 30 cm high with the water surface, it will be different from when you hang it up.

The lights are close to the lake, not to mention the arrangement of many lights in the background, but the foreground is lacking, and the bulbs are black or reflect poorly…

#2. How to calculate the amount of light in PAR

How to calculate the amount of light in PAR

PAR (Photosynthetically Active Radiation) roughly translates to photosynthetic light radiation, more specifically, this is the amount of light that a plant can use for energy. This is the most accurate measurement of aquatic light.

1 PAR means 1 million photons of light hit 1 square meter in 1 second, abbreviated as micro mols. If the PAR measurement at the base of the lake reaches:

  • 15 to 30 micro mols: your aquarium is low-light, no need for CO2 and nutrients. Most mosses, ferns, nanas, and easy-to-grow cuttings will do well in this light.
  • 35 to 50 micro mols: your tank has medium-light, most aquatic plants do well with this amount of light. However, you also need a moderate to high amount of CO2 to keep plants healthy and avoid moss.
  • 55 to 75 micro mols: your tank has a high light. Most aquatic plants do well and grow quickly in these conditions. Supplementing CO2 and nutrients is extremely necessary to avoid moss.
  • Above 75 micro mols: your aquarium has extremely high light, moss, ferns, and nana should not be planted in lakes with PAR above 100. Providing abundant CO2 and nutrients is a vital condition in lakes.

PAR is affected by bulb type, reflectivity level, and also Ballast. To measure PAR, measuring instruments were very expensive, up to more than 4.3 million USD, now PAR meters are widely available and cheaper (about 430 USD).

Read more: Recessed Lighting Calculator – How much light is sufficient?

Note when using light for aquariums

Note when using light for aquariums

  • The time to turn on/off the lights is suitable for the creatures in the tank. There are 2 ways: continuous lighting (8-12 hours) and intermittent lighting (4 hours on, 4 hours off).
  • Based on the organism as well as the plant color choose the light color of the lamp.
  • Regularly observe aquatic plants to know the condition of the plants. Signs, when plants are underexposed, will be pale and need to add light immediately.
  • You need to consider carefully using the right light when you want to use decorations for the aquarium. Because some aquarium decorations can amplify the light or reduce the light level.


Above is the article about Aquarium Lighting Calculator and other related issues. Hopefully, our article will provide you with all the necessary information to easily take care of the best aquarium.

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