How Many Watts of Light Per Gallon for Your Aquarium

By Eddie Waithaka @aquariawise

How Many Watts of Light Per Gallon for Your Aquarium

quarium enthusiasts often ponder the best ways to light their tanks.

Some may think that more watts of light are always better, but this is not necessarily the case. To find the best lighting for your aquarium, you must first understand how watts of light translate to gallons of water…

Plus, with the advent of LED aquarium lights, you’ll also need to know how many lumens of light you will need per gallon of water.

So, how many watts per gallon of water is ideal for your fish tank?

Well,…

1 to 2 watts of light per gallon of water is recommended for a freshwater, fish-only aquarium or a low-light planted tank. 2 to 4 watts per gallon is best for a medium-light planted tank, and 4 watts per gallon is ideal for an aquarium with high-light plants.

0.25 to 0.5 watts of light (10 to 20 lumens) per liter of water is recommended for a freshwater, fish-only aquarium, or a low-light planted tank. 0.5 to 1 watts per gallon (20 to 40 lumens) is best for a medium-light planted tank, and 1 watt per liter (40 lumens) is ideal for an aquarium with high-light plants. About 160 lumens per gallon.

Fish Tank SpecsWatts Per GallonWatts Per LiterLumens per Liter
Fish-only Aquarium1 to 2 watts of light per gallon of water0.25 to 0.5 watts per liter10 to 20 lumens
Low-light Planted Aquarium1 to 2 watts of light per gallon of water0.25 to 0.5 watts per liter10 to 20 lumens
Medium-light Planted Aquarium2 to 4 watts of light per gallon of water0.5 to 1 watt per liter20 to 40 lumens
High-light Planted Aquarium4 watts of light per gallon of water1 watt per liter>40 lumens

That said…

Please note that aquarium light wattage and lumens per gallon only serve as guides. Other factors, such as fish tank depth, water clarity, and the height of light from the tank, matter when considering aquarium lighting.

So, in the rest of this post, we will explore the different aquarium light insights and help you decide which one is best for your aquarium.

Watts of Light Per X Gallon Fish Tank (Aquarium)

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