Moss appearing on Roxall fiberglass

I currently have a couple of problems. . . I got brand new clones, they were poorly taken care of.. I have about seven that have bounced back and are doing wonderfully..the other ones are not doing very well though.. they are droopy, yellowing - in no particular pattern some yellow at the top some yellow at the bottom in the middle.. it seems as though their growth is stunted..but i feed all of the plants the same..test the ph everything.. then on top of that they are being grown in fiberglass (Roxall) and the fiberglass that was yellow last week is now turning green..it is almost like moss. some have suggested the plants are eating themselves..others have suggested overwatering..really not sure what to do at this point..even the ones that are growing big have the green in the pots..

The green is probably algae, I've never heard of moss in someone's grow. Probably could happen but moss grows very slowly. Control algae with algaecide and limit the light reaching your medium.
Here's how I do it. Also, notice the black tube covering the recirculating line on the floor. It's a clear tube with black drip line slid over it.