Pick a light, set its intensity and every channel the way you set them in the maker's app, and see the spectrum that comes out, as the maker's own published graph draws it: which colours, how much of each, and where it peaks. Add a second light to see what the pair gives together.
The comparer itself needs JavaScript. Everything it draws is worked from the data described below.
Each light is shown at full power exactly as a published spectrum graph draws it, its maker's wherever the maker publishes one, read point by point. How that total splits between channels comes from a model of the maker's LED list, fitted to the same graph. A light set with a knob rather than channels is shown at the ends of the knob its maker's graph draws, blended in between, and its page says what was assumed to do that. A light whose curve cannot be split, with no LED list or a graph that may not match one, is shown as one curve with Intensity only, and its page says why. In the comparer the scale's 100% is the tallest bar the picked lights give at full power, so turning any light down lowers its bars; each bar's share of all the light is in the readout and the table view, which also gives the watts, on one scale for every light. The watts are the light's electrical draw shared out along its spectrum, not watts of light. Makers' graphs are marketing drawings, so any peak can sit a few nm off.
reeffrags.com is not affiliated with or endorsed by EcoTech Marine, AquaIllumination, Kessil, Red Sea and ATI. Each light's page credits the graph its spectrum was read from.
This is an estimate built from a few hobbyists' readings, not a measurement. The range is wide on purpose, because those readings disagree, for some lights by nearly two times, and one owner's corals burned at a step the low end called small. It is for the spot right under the light; anywhere off to the side reads lower. A PAR meter reading beats it every time. PAR here is in µmol per square metre per second, the unit a PAR meter reads.