Please check post #12, you will find a chart of 6,700K PAR38 bulb with high reference. However, all values are in PAR not lumens because lumen is a unit for human eyes not grow light.
I did look at that and while I do appreciated the help, I do not understand chart chart at all.
I simply would liked to hang two PAR38 6500K bulbs from pendants above my rimless 40gal tank 37x15x18 and I just need to know how high.
I'm sure from an enters standpoint all this is great info. But, I think a lot of it is lost on most of the readers.