I decided on colors for the wall: Semi-gloss "Campfire Ash" paint for the background. It was supposed to be a light gray color. I think the mixing machine at Home Depot was a little out of tolerance, because I can sense a hint of sage green color, but it's mostly gray. For the tube supports, I went with a color I had on hand: MEGA BLUE! It's almost the same color as blue painter's tape. Hopefully the semi-gloss paint background will reflect some of the light coming from the PEX tubes when this thing is operational.