It's just an overall poor design on marineland's part. You can never turn off the blue moonlights while running the white lights and you cannot hook up the moonlights to a timer.
Also the whole 18-24" or 24-36" etc. thing bugs me. Just list the size of the fixture! The expandable legs usually sag when you have them all the way out too. And make a 48" already!!
Also, the light output is merely ok. I think they should be brighter.
But, overall I think they are nice and are good if you're looking for a ready built LED fixture and aren't expecting too bright a light. They look cool, very sleek. I just have those couple of complaints about them I listed, if they fixed those things this fixture would go from "good" to "excellent."