how can i bring my zoo's color back?

[gotbags-10]

I've had my 24g ap for a year now and have collected quite a few zoo frags since. Some of them are doing fine but a lot of others have lost all their color and im not sure why. I keep up on water changes weekly 2 gal with IO reef crystals. I dont add any supplements either. I changed out my stock 2x32 pc's about 6 weeks ago. It seems like my greens are the only ones that have kept their color. I'm kinda hesitant to buy any new ones right now because of this. Any suggestions?