A challenge ---- who can diagnose this plant? Answer tomorrow.

This is a test of general growing knowledge, for those who pine for their days back in school, studying drugs, sex, and alcohol.
The following plant is 4 months old, grown indoors in soil, with one other plant who made the fatal mistake of being a male and is gone. This is the first time I've tried to grow so I don't know jack shit about growing, but have been reading forum and learning the basics. Grown under mostly CFL, about 300W total, 400W currently for flowering, using T5's and household bulbs, along with a 135W UFO LED. On sunny days, I was placing the plants outside for 3-4 hours to get sun until about 2 months old when I noticed fungus gnats on smaller plant. Quarantined that plant until I "thought" gnats were gone, instead infected other plant with gnats, the one pictured below. After about six weeks, those gnats are now under control (gone, I think, pray), having used a combination of Neem foliar sprays and keeping soil covered. Being a newbie, different nutes have been used along the way, including MiracleGro grocery store stuff, Stuart's 10-15-10, Maxi-Gro and now Maxi-Bloom, supplemented with dolomite lime in potting soil during repotting at 2 months, she was seriously potbound, and regular magnesium with feeds (MgOH, or Milk of Magnesia, used as ph buffer..... don't ask....., otherwise tap water is good pH and I allow CL to evaporate). I feed 1/2 strength nutes, every other water, and let soil dry out between waterings. (Clue: not water issue) First half of grow I never checked pH. I then first noticed this problem on both of my plants, worse on my male runt, checked pH which came back way too low. So that was when I repotted (since also had just discovered gnats and figured would help get rid of them, too) and I fixed pH (ongoing problem, for some reason, soil wants to keep getting more acid, I read that organic soil does this?) which seemed to mostly solve the problem. I have a 10x magnifying glass, inspected leaves for signs of bugs several times along the way, have never seen anything.

I posted about a week ago with pics when I was pulling my hair out, and most feedback was that she had nute burn. I flushed her with no improvement. She was losing all her leaves at this point, had lost at least 1/3 of leaves, maybe half, and was 3 weeks into flowering. A couple days later, when I was ready to throw her out in frustration, I stumbled onto a post with just one little comment, on this forum, that made the lightbulbs go off. I'm happy to say that she is now recovering nicely.

So here are some pics previously posted, though now posted more helpfully I think:
Two months old, healthy girl:


One month ago, still looking good despite problems along the way. Posted because was trying to scrog and broke her in half. Yikes! She did fine.

Same problem in male plant at two months, who was a sickly runt from germination. Key clue (I've found) is spots occurring along veins of leaves:


Picture of female one week ago. Notice leaf in forefront of third photo. It fell off within a day or two. The leaves were falling off easily. The lower young leaves would come in yellow and look affected and those closest to the lights also looked the worst. I had 500W (actual watts) running for the one plant last week. I apologize in advance for picture quality.


Here she is one week ago, three weeks into flower, notice how many leaves she lost. Waaaaa!

A few more pics along the way:

Anybody want to hazard a guess? All the info needed is buried in this post, though its tricky.

I'll post the answer tomorrow. Until then, my lips are sealed.

You just threw nutes and water on without knowing what the ph is. Starts off ok but as time goes on and you feed with high ph water/ feed eventually the ph goes out too much and results in lockout of multiple nutes, thats what you have here, also the damage is done and cant be fixed.
Buy yourself a ph pen for $20 and ph adjusters about $15 for the next grow.

giving nutes too early read https://www.rollitup.org/marijuana-plant-problems/488004-guide-nutrient-deficiency-toxicity.html

Only two souls brave enough to attempt to make a diagnosis??? This was a hard one, granted, why I posted it. I thought some people might like the challenge and to test their diagnostic skills. I knew saying I didn't see any bugs with the magnifying glass would throw people off, same as it did for me...... but I didn't see any so it needed to be included. I tried to make it like "grand rounds" in medicine.

The problem I had was spider mites. Yep. Stumped the hell out of me too when I couldn't see any bugs. The post I read that sent the lightbulbs off mentioned that sometimes you need a microscope with 30x or higher magnification to see the mites. I still haven't see the critters but since treating for mites my plant has made a miraculous recovery. It also explained that often leaves look worse closest to the lights, as if they were light burned even though I was careful not to allow the leaves to get too hot. It said that spider mites like the warmth and dry of the leaves closest to the lights so they hang out there. Most posts had said you can see them crawling around with a magnifying glass or when you knock them off. On my plant, that did not work, and I looked at least three different times, very closely. I also never saw any signs of webs. I've had spider mites on other plants in the past. These must be a different species because I could always see them. There is no doubt in my mind though that it IS spider mites. The spots are classic and the , including the past improvement when treating the fungus gnats, confirms the diagnosis.

Also, I've had them quite a while but also had fungus gnats, which I could see so I knew about them. When I treated for the fungus gnats, I temporarily saw improvement because the Neem I used also inhibited the spider mites. However the fungus gnats all died while leaving some mites alive, so when I stopped treating for fungus gnats, the spider mites returned with a vengeance.

pH is not a problem at this time, though it has been off in the past. I'm not sure if it caused problems or not. It's tough when the picture is complicated by multiple problems. What kept me looking for answers was being told I had nute burn when I was sure I hadn't overfed (besides the lack of improvement). In fact, I'm concerned at this point that my plant has been underfed and is suffering from a mild nute deficiency, and wondering if I should add nutes every feeding for a while???? She seems a little pale green for my liking. But praise the Lord, leaves are no longer falling off and no new spots or diseased looking leaves.

Besides question about if I should up the nutes temporarily or not, will her being skimpy on number of leaves hurt the flowering and budding? Is there anything I can do at 4 weeks into flowering?

You need K during flowering so look for a nute for bloom or flowering, dont overfeed nutes give like a capfull you will need to flush last 2 weeks to get rid of bad taste from chemicals.