Aquarium lighting calculator

The calculator converts the aquarium dimensions to centimeters and multiplies the bottom footprint by a planning factor. Low-demand plants use 0.7 lumen per square centimeter, moderate-demand plants use 1.2, and high-demand plants use 2.0.

Entered water height is used to calculate approximate water volume and lumens per liter. The total lumen recommendation is driven by footprint because a longer or wider planted area requires the fixture to cover more surface.

Low-demand guidance suits many Anubias, Java fern, mosses, Cryptocoryne, and other shade-tolerant plants. Moderate demand is a useful starting point for mixed planted aquariums with common stems, rosettes, and easier carpets.

Use the high-demand profile for dense carpeting plants, demanding stems, or layouts where strong coloration and compact growth are priorities. Higher light also increases the importance of stable CO2, nutrients, flow, and maintenance.

Lumens describe visible light weighted for human vision. PAR describes photosynthetically active radiation, while a PAR reading at substrate level shows more directly how much usable light reaches a plant location.

Two fixtures with the same lumen output can perform differently because of spectrum, lenses, reflectors, beam angle, mounting height, aquarium covers, and how evenly the light spreads across the footprint.

A deeper aquarium can need more focused optics or a stronger fixture even when the footprint-based lumen estimate is unchanged. For tanks deeper than 60 centimeters, check manufacturer coverage and PAR information at the intended mounting height.

Avoid solving every plant problem by increasing light. Poor CO2 stability, weak circulation, nutrient limitations, shading, or unsuitable plant placement can all cause slow growth while stronger lighting increases algae pressure.