Leaves are green but are showing little brown spots on the lower leaves.

Im growing in coco and on my lower leaves I am starting to see little brown spots starting a little before the tips any suggestions as to what's kinds of deficiency this might be ?

Pics? Could be overwatering, calcium/magnesium defiency/lockout or nute burn. Hard to say without pics. Probably one of those three through.

some pictures would be very helpful for these experienced growers to diagnose your problems... also probably, nute lineup, PH, etc...

Ph is 6.3 and im using an nutes but there tiny brown spots....I no using the coir is like hydro so it could be cal/mag ...when I did soil I almost always had to add cal/mag after a little time....ill try and post some pics asap. Coco is new to me so I definitely know not to treat it like soil ...ill up the cal/mag a little more as I was only using 1/4 strength cuz the plants went into flowering 2 weeks ago