Great yield? So you have 5 of those lights... 15 actual watts each for a total of 75 watts. So under those 75 watts what was the total dry weight of that harvest?
8 oz.
I have 5 of these lights on ' this grow ' previous I had 4 lights for 4 plants closed in a 36"X72" tent with reflective paneling on all sides. Total 60W = 6000 lumes. More than effective.
Back to the point... You said you " can't flower under those lights " ...
I said you are incorrect not trying to be a jerk I'm just saying that YES you can flower just fine under these lights. And I'm also not the first, there are many people who have grown and still grow using these.
I grow for personal use & pleasure not to supply a dispensary lol so if you are going to say 8oz isn't a great yeild off 4 plants in such a small tent with such low wattage than we are speaking different languages.