5th week flower Brown spots Heat/light stress?

[RubySlippers]

Hey all,
I'm in the the 5th week of flower. I've been seeing this issue get worse for 7-10 days. I had a problem with the heat wave we've all been talking about. I finally got a portable ac unit in and temps are under control, I think. Anyway the first two pictures are of the same plant. I flushed her two weeks ago because she had what could have been nute burn (yellow leaves that turned crispy, curly, and brown and eventually fell off). I flushed with 1/4 strength nutes. A week later I removed the MH bulb and put in the HPS bulb. Since the flush the ph at the roots has fluctuated from 6.8 to 6.6 back to 6.8 then 6.2. Around the same time as the bulb switch I did a heavy defoliation. I think it was shortly after that that I noticed the start of the brown/rust colored spots on the leaves. It seems like the spots are mostly on the top of the plant. The light is probably too close, but I'm out of head room until I can figure out how to hang the hood from the ceiling without brackets or ratchets. Im not sure if this is a heat/light issue or nute deficiency. The bad leaves are creeping to the top of some pretty bud-laden colas so I really need to figure this out. New growth at the bottom is green for the most part, but there are definitely some little yellow leaves that wilt and fall off. Any ideas?

The other two plants look pretty good. But the buds are looking heat/light stressed to me. (See the third pic below) Would you agree? Like I said, the temp/rh should be in range starting today or yesterday. Maybe the problem will correct itself? I really wish I would've tried some kelp or something to help with the heat. Next time!

Thanks in advance for any ideas! I couldn't have gotten this far without you guys!

[PaganRich]

Man, I hear you re: this one....exactly same problem and have got rid of it but there were a few culprits that may have been involved/ supporting this problem....there is a fungal problem called rust which hits overly warm/ high humidity grows with dead zones in air movement...getting humidity down as well as heat and improving air flow counters this but this does give rust staining like spots but what I found really did it was heat reduction (and this can be running lights during the night-time for example), steady constant air flow, nutes reduction and checking for light stress plus plant drainage......I worked on all of these and even took a 600 lamp out of a 240cmx 120cm room, leaving only 2 x 600 behind (3 x 400 just didn`t cut it).........but I`d say here to work on nutes and heat and I reckon it`d go...just some thoughts

[alltatup]

Ruby, it's not a flush with 1/4 nutes: Flush her with pH'd water. And what Pagan says.

[RubySlippers]

PaganRich Does this still look the same issue you were dealing with? It looks like bud rot to me. It has spread too all 3 plants. I posted an update a minute ago in a new thread that addresses some of the stuff you brought up. Thanks for the info and advice!

[RubySlippers]

alltatup Nebulas tutorial on flushing sick plants says 1/4 strength nutes. On other sites I've read that it should be plain ph'd water. I basically flipped a coin and went with Nebula's advice. The ph has been consistently in range since the flush. The last time I flushed (mid-veg) I used plain ph'd water and the results were not great. But something else may have been going on at that time. Thanks for your input! It's nice to hear what has worked for others.

[GenghisGreen]

How many different strains are you running? All experiencing the same symptoms?

[RubySlippers]

Two different strains...same symptoms. White Widow and Papaya.