Our research and development professionals discovered early that PVC pipe products were renowned for experiencing problems with plant viruses(pathogens) recurring in the garden systems. Poor plant growthseemed to occur even when growing conditions seemed "perfect ". FHD once again corrected the problem. The solution, "Plant Tier™" System* PVC growing tubes and stands are treated with "titanium dioxide". This protective coating eliminates the problems experienced with disease recurrence in the root zone, as well as significantly limits the effect of "UV" rays making untreated PVC brittle and porous over time.