I didn't read all the responses carefully, but it's a good idea for people new to led to look into DLI. I have some plants drooping towards the end of their 18 hour veg period at 50%, while others are still praying. The amount of light a cannabis plant can take is genotype specific, you can make some generalizations, but everything comes down to the specific plant, not strain, plant. DLI will help you properly adjust from lower %s during 18 hour veg cycles to higher %s during 12 hour bloom cycles. So will a Par meter, but if you can't spring for one of those, a $30 lux meter will give you consistency when you flip from 18/6 to 12/12, you just use the meter and adjust your light % and/or height from canopy so the plants are getting the same lux, then slowly adjust upwards from there, over a period of days/weeks to the maximum your plants can take. Keep notes if you find a cut that you like, so you can do even better in the future, and good luck!