Light brown spots on fan leaves

Chongman in your case that looks like a ph imbalance or nute lockout....just a quick guess without alot of info. :)

I don't see any mites or silk or anything anywhere. And like I said I didn't notice this until after I gave it a last big dose of FF Grow Big. I did overdose it on GB throughout veg as it seemed that it liked it.

I have 92w of CFL (in 1 rubbermaid) at the top and this leave is not really at the top. There is other foliage above it that looks good except for a part of one smaller leave that grew into one of the lights overnight. :wtf:

I have another plant in the same space that I thought was from the same bag seed but doesn't look similar at all. It's a more stretchy plant with probably 3 to 5 times the space between nodes(still not a lot of space, just the other plant has super dense nodes, I'm almost thinking lowrider?) and it seems to be doing fine. But it's in a pot that's 2 or 3 times the size of the spotty plant.

I'm like a week into 12/12 so I guess it's not a bad time to just flush and then give the beginning flowering ferts again(first feed for one of the FF ferts is bigger). The FF flowering ferts contain some nitrogen so I guess it should get everything it needs.

I'll also wipe the leaves down and maybe spray the leaves down with water daily just in case it's mites, because the water might at least keep them in check.

Oh yeah I forgot to mention that I'm using R/O filtered water.

I think it might be leaf spot fungus and if it is you don't wanna be wiping water on your leaves regularly

That's not spider mites. The blotches are WAY too large. Mite damage presents first as tiny speckles high on the plant, especially in hot grow rooms. If that were insect damage, I would lean towards thrips instead. The pic is a little blurry. Can you steady your camera better so we can get a clearer picture of the damaged leaves?

It's also not Magnesium, which presents as pale striping between the veins, in a very regular pattern that is easy to spot.

You need to be adding CalMag Plus and doing regular soil runoff pH tests if you run RO water. And you need a gallon of medium per foot of main stem. If you suspect rootbound, why are you waiting? Happy feet makes happy plants.

The plant's doing well now. That one leaf is still a bit blotchy but the plant is in the stretch and bud sites are popping up all over, no more leaves have become effected and all the new growth looks good.
The other plant started to show classic signs(I think) of nitrogen fert burn with yellowing leaves starting at the tips. So I think over ferting had something to do with the spots even though I don't know why it would be manifested as these light brownish spots.

But both plants seem to be doing really well, they are growing like crazy on about the 11th or 12th day flowering, except for the fact that I broke the main shoot! http://boards.cannabis.com/plant-pro...in-branch.html

I'm aware that foliar feeding with fertilizers have the ability to burn leaves a bit as well. Especially if they are near the lights..