I have watched a few videos about mounting the radions xr15's. I have a 48x24x16 lagoon and light spacing a height. First I got a xr30 pro g5 (for sale nib), but decided to go with 3 xr15's, 2 blue's on the outside and 1 pro in the center. I think my biggest question is on the height, Radion recommends i believe something in the 7-8 inches of the water. Do i still do the 7-8 inches even thogh im only 14" to my sand bed??