they say a 1 ft to 2 ft is good for maximum results
Trust me on this one, lower them. I just finshed a grow using two of these panels for a 2x2 area, except I also used a HPS, two 55w PL-L purple flouro fixtures, one 2' 8 tubed T5HO fixture. I also hand built two LED fixtures using CREE XLAMP emitters, these LED's you can have a foot or so away from the plant. But these goofy 225 LED panels that your using aren't in the same league as CREE XLamp LED emitters like that of the Procyon100
My last grow was to determine how much light is to much before diminished returns, as I was planning a growall, so I really needed to do some testing for that project. This test, also showed that the 225LED panel you have would be better served if used with other lighting to satisfy the high lighting requirements that some plants require. In fact, some of the foliage touched the 225led panels, not one burn or scorch mark like you would see if a leaf touched a CFL.
I used the same type of panels your using for my rear wall side lighting. They should be closer to the plants than you have them, ignore the manufacturer recommendation. The only thing you need to look for is where the light is penetrating, then determine the best distance for the panels. But you must move them closer than you have them currently.
Those manufacturer recommendations must be for a low light plant. The plants we grow are anything but low light plants. In fact, the 225 led panel produces virtually no heat at the 5mm LEDs so this in itself is useful, fo me getting light to the lower portion of the plant was the best use I found for these 225 led panels, they may not be the greatest grow lights, but they can be used effectively when used properly, so lower then a bit