Crispy, Tan Leaves? Dirty Bulb?

Hey gang, my friend had a grow and it all went to crap because he is having the same problem i am currently having. I am now using his light and I think it's linked to that. It's a 400 watt HPS.

I observed him foiliar feeding his plants many times while the light was on and close to it. I believe that the problem we are having is that the water molecules are drying on the bulb and creating a magnifying glass for the light and its burning our plants.

Does this sound about right?...
What's a good method for cleaning my bulb?

Or, the water molecules are on the leaves and therefore creating a magnifying glass on the leaf itself therefore burning itself? Pretty sure that's whats happening so if you are going to foliar feed make sure to do it either after the light goes off or before the light goes on.. so you don't burn your plants.

How about actual distance from the light itself? U sure u don't have it too close? Sounds like ur burnin em

I'd say 6 inches or so from bulb? I'v done grows in the past and we never had this problem , my friend grew NYC Diesel and had this exact problem , tan cripsy leaves. He then gave me 2 clones from it and i grew them out, now getting the same exact problem. (Using his bulb/light).

I guess ill try raising the light abit but my friends light was pretty far away from the plants and he got the same problem.

I took a lint clothe to the bulb today, hope that helps.