i have a sea of green grow box from pcgrowbox and got the 300 watt led upgrade.so far things have been really good except the last few days.the leaves have started to get yellowish brown tips and along the edges.this hasnt happened to all of them just a few.first off i started them on the floragrow last week and around the same time i was messin around trying to get my box light tight.i seen on the pcgrowbox site they started selling this thing called the skunk box.it is basically the same setup as mine but with a few alterations.i saw it had a cover on the front of the box that made the box light tight.you guys can get on the site and see what im talking about.anyway i decided i could make 1 very easily so i went to walmart and got a windshield cover.i found one made exactly like the lining of my box.i mean right down to the thickness and imprint on it.i cut it out and with a few pieces of velcro i made the exact same setup.now it has been around 5 days since i watered it with floragro and made the light cover and the leaves are starting to turn.what caused this the floragro or did the cover do something to the airflow or what?i am using foxfarm soil.i keep my light between 6 to 8 inches from plants.i am growing 6 plants in all.3 of them are 60 day wonder and 3 of them are pineapple punch.all are auto's.the plants have only been up around 2 weeks and have started the fourth set of leaves.this is my first attempt at growing please help.also what do i need to make a trellis for my system or a sog screen.can i buy the whole things or do i have build them?