As for your algae problem, your net pots may be your problem. The net pots I use are solid on the sides for the top couple inches. Your net pots are net all the way up the sides. This makes it hard for the clay pellets to block all light.
As mentioned before, white PVC can pass light if intense enough. Always a good idea to light proof PVC pipe.
If using RO water, add a UV filter to kill any algae in your source water.