Brown spots and leaves getting slim

[Pcatran]

Hello all,
I have a grow cabinet with 3 cfl lights, and 3 plants of different types. All three are getting the same phd water 6 - 6.5, temperature if around 28oC and umidity of 55%. All have grown, and one of them has passed to flowering stage, while the othera are in vegetative. Now i have changed the light regime to 12h x 12h to make all go to flowering.

Everything was ok, until my first flowering plant began showing brown spots on the leaves, that eventually dry and die, and leaves that turn very thin and slim.

I suspect it is a borum/ magnesium/ calcium deficiency, however since i have killed other plants in the past due to excessive nutes, i am worried about trying to feed them. I have flushed the system with 3x the volume of water, but it didnt solve. How can i post pica here???

Please help?

Thanks paulo

 

[NuttyProfessor]

link a the bottom of my sig " HOW TO UPLOAD YOUR PICTURES"

 

[Papageno]

Flushing doesn't help a deficiency problem, just makes it worse.

Many things can cause what you are describing. Pics will allow us to help you without listing off everything like a sticking on here that explains the problems.