This doesn't make sense to me since light companies give yield stats in grams per watt per square meter. The more watts = more weight is the way I understand it. I do know that a lux meter should read 50,000 - 70,000 lux at the canopy at different stages of the plants life. I'm unaware of a watts into lux conversion though.ok, that explains it. When you feed bottled nutes, you must start very low. I great rule of thumb is, PAR = Nute PPM.
So, if your plants are getting say 350 PAR, then Your target for nutes should be 350 PPM PER WEEK.....
Now, plant age is also PAR specific, JMO. ( just my opinion ) Giving it more light then it can process, is a waste. You dont feed babies a whole chicken, and you shouldnt feed small plants a giant plate of food either.
By staying with the above information, you will never over feed, OR over light your plants. Hope that makes sense. LED lights can be decieving, so get a LUX meter. Alot of growers are using more electric then they need to be, ..