brown spots on fanleaves

Hello,

I would like to ask what the problem on the picture could be? ph -> calcium? This appeared more or less over night, looked fine 2 days ago. only the top large fanleaves are affected, new growth is fine.

My runoff ph is at 6.4
temps 24
humidity 55%
hps
fertilizers: AN
2weeks into flower

any idea?
thanks

Edit: calcium, mn, or zinc.. flush at correct ph 1/2 str nutes.. what medium/nutes you use?

hi, thanks.
I use a coco/soil mix and the basic advanced nutrients series. Sensi bloom, big bud, b52, nirvana

elTopo85 said:

hi, thanks. I use a coco/soil mix and the basic advanced nutrients series. Sensi bloom, big bud, b52, nirvana

Click to expand...

One coco charachteristic is its increased need for calcium as it is held onto by the medium. Adequate runoff and a calcium/mag supplementation are helpful. Spots can indicate light burn or pests also.

It's probably calcium, then.. AN doesn't skimp on micros, in what I've read.

If cal/mag fixes it, tell us! I want that pic saved for calcium def..