Lighting requirements

I use the app "PPFD Meter". It is very useful. Without calibration the app is not 100% accurate but it's pretty close. If you search for "PPFD chart" you will see a chart that allows you to set the illumination level depending on how many hours a day you run the lights. We can not comment on your lighting without knowing how large an area you are trying to illuminate. 490 watts could be too much for a small grow area or too little for a large grow area. Using the PPFD app and the chart you can adjust your lighting level properly.

Each light can cover a 2 x 2. 20% for seedlings. 40% week 1 to 3 60% week 3 to 6 80% early flower 100% mid flower 80% last 10 days That will keep you right.

Light plants use to drive photosynthesis is measured in (Photosynthetic Photon Flux Density) or PPFD, You will need a PAR meter if you would like to really dial it in but they can be costly. However many hours of daylight you have, you will need to break it down into seconds, 18 hours is 64,800 seconds, multiply the number you get from your PAR meter by the number of seconds of daylight. You want to get as close to 40,000,000 million moles this is as much as the plant can use on any given day. I do not know about the app, but I do know you even the cheapest PAR meters can run 100's of dollars, and best dip into the 1000's, I doubt the tech exists within an app, It is possible to use Lumen from a LUX meter which is 30$ but it requires a little mental gymnastics, they may be using a lux style sensor then doing the gymnastics. The thing about LUX is it measures in lumens which is the metric for the human eye, not plants. I dropped 200 on a cheap Korean PAR meter. Seems a lot but the time it saves in guessing, is hard at first to feel its value the longevity of the device, simplicity of use, once the decision is made you will continue to grow, idd say it's worth it, until your certain though.