What is this on my leaves?

Hi all! So I am about a week into flowering my NL fem auto and noticed this stuff showing up on the big fan leaves a couple of days ago. I have her in a 1 gal pot with ffof and I have added no mutes. Any idea what it could be and should I be worried? They appear to for now just be on the fan leaves. I read that maybe it's a calcium deficiency? I have been using ph'd water. Looking forward to everyone's thoughts.

Mine did the same thing so I ended up getting cal/mag and a ph kit. My water ph was all over the place. It seem to have stopped the problem.

Where do u get cal mag? How do you apply it? What kind of ph test kit did you buy?

I got it all from Amazon, ph tester, ph up and ph down, and the cal/mag. Overnight shipping was like 5 bucks. I mixed it in water and got the ph to 6.5. The water was at 5.0 before I added the cal/mag and then it shot down to 4.0. No good, had one plant lock out for a while before I knew what was the problem. But live and learn it will be ok

Thanks dude, I'm just scared to try and fix it and induce other problems. I'm at the home stretch and don't want to lose my buds.....of course, those all seem to be doing fine. I'm just worried about this spreading.

Mine got this bad and he's still ok, but you got to do somthing or it could go from bad to worst. Mine started with the small brown spots like yours

Are you growing autos? How old is yours? Does the cal mag help adjust ph?

Yeah that's an auto candy cane, mine are 8 weeks right now, prolly going to need three more weeks or so. The cal mag and adjusted ph helped out a lot. Bad ph can stop you nute from working properly. What kind of water are you using, and what nutes and how much.

No nutes, and I say ph'd water but it's really just tap water I left out for 48 hours.