Brown Spots on my leaf + rep for help!

I was doing some work with my girls this morning and found some brown spots on a leaf. So far only one plant is showing these spots and they are on just one of its leaves (I checked all over her to try and find others) but I was hoping someone could give me some insight on this issue. Im assuming its PH imbalance considering I ran out of PH up last time I watered so im hoping this is all it is as I have picked up a huge bottle of ph up (not running out again anytime soon) and flushed with water (PH 6.8 ) +rep if you can give some feedback! The first three pics are of the top and the fourth is of the bottom.

Brown Spots..

my first though is ph is off i shoot for 6.0 in water and dirt, make sure you flush with phed water @ 6 and also ph you nutrient after they are mixed, you can also check the ph of the run-off to see if you soil is to hot, flush with plain water phed @ 6 and see if this stops the necrosis

LT1RX7 Drifter said:

my first though is ph is off i shoot for 6.0 in water and dirt, make sure you flush with phed water @ 6 and also ph you nutrient after they are mixed, you can also check the ph of the run-off to see if you soil is to hot, flush with plain water phed @ 6 and see if this stops the necrosis

Click to expand...

Thanks for the advice! I checked the run off and the soils about 6.5 so im thinking the off balanced PH from my last water is the problem.

I've had this happen if water gets on the leaves and the light burns them. Also if nute water hits the leaves, could do the same thing.

water will evaporate most times before damage is done, but nutrients will for sure due to salts, shit i have taken veg plant and put them in the shower for a bath and put them back in the room after a short drip time so my carpet stays dry and have never had a water burn problem, but your water is different so it may cause some burning due to desolved solids