Weird spotting on some of my leaves!!! Please help

So this is my second grow with this strain rocklock. All of these plants were grown from clones in ocean forest soil. I have been feeding every third watering according to Lady Z's feeding schedule over on planet skunk using botanicare products (pbp grow, bloom, liquid karma, and cal mag). PH is always kept between 6.4 and 6.8. Using r/o water that is supplemented with cal mag up to about 100 ppm at a .7 conversion. They are just starting their 4th week of flowering. Temps are a little low at 65 and humidity is high at between 60 and 70 but there is little I can do to fix this because the grow is taking place in an unfinished basement.

These weird spots happened to me last grow as well. It only affects a few of the leaves on a few of the plants, but seems to progressivly get worse as flowering continues. The leaf develops these brown/black spots and then the whole leaf turns rust colored and gets all dry and brittle. The leaves are generally in the middle of the plant. I thought it might be bugs, but I can't see any and it doesnt really seem to spread to the rest of the plant. Any ideas what it might be?? I would greatly appreciate any help. I'm stumped

Ocean forest has nutes in soil they say not to give nutes for 30 days. I use it only for my moms & soillness meduims for flowering. Peace

Im sorry I miss read! Your in 4th week of flowering...My bad...Im looking at My (Marijuana Garden Saver) by Ed Rosenthal. It looks more like nitrogen def. But dam Hopefully someone is more helpful than my High ass. Peace bro.

Thanks for taking a look. Yeah they are pretty far along, this strain doesn't need much nutes. I was thinking nitrogen deficiency would give it a more pale green color starting lower on the plant...at least that my novice understanding of it. Its not killing my plants, whatever it is. But it can't be good....

I have the same problem but I thought my light was to close and I was burning. Since this is my first grow I was not sure but also not to concerned but now I am

same thing happened here. i was told it was under ferted.

First look, I would guess phosphorus def.

did you inspect the roots from your last grow? did they look brown?

they r K (potassium) deficient, double ur bloom ferts

So i guess your plaant has a nitrogen, potassium, and phosphorus deficiencies along with being under fed.

just realized someone before me dug up this post from feb 27th, these plants r probably done by now or close to it.