I have no problem with growth now that I have been keeping my parameters in close check
a little of this alittle of that and things seem to fall into place . I have actually been logging my results on a semi-daily basis and have noticed some trends and this is actually what has helped me fine tune my gh setup. Its really amazing how little you have to add of something to notice a difference. The age of my system cant hurt either. coraline took a good year to take hold and now it grows fast . I did away with the sun block cloth in the fall and am debating on wether or not to put it back in the summer . the only reason would be to help cut down on heat gain ,not for light intensity. your ? plastic or poly-carb, well I think its mainly a cost issue and not a light issue