What do the plants need Many of the sites in the AquaPlant index specify the amount of light needed to grow each plant in their gallery. And most of them use a qualitative grading like low, medium and high. Yet few of them specify how much light you need for a plant that needs high lighting. And probably they don't fully agree on what high lighting is. This is definitely not quite correct but in practice it seems to work reasonably well.
Some sites always specify a single value for light requirements but some specify a range of values.
The latter is generally more useful. This list is from Erik Olson , and you can read a lot more about aquarium light at the Krib . But if you use full spectrum efficient fluorescent tubes, have a standard type of tank, and don't use large amount of peat, then things are a little simpler. Here we will introduce a simple model, that can give you a rough estimate of the level of light in your aquarium. You can use the model with the calculator below.