Yellow Spots on Lower Leaves -- Help Much Appreciated!!!

Setup Information:
2 DWC's (Kush and a Haze) using 5.8-6.3 ph
1 Auto (AK hybrid) in FFOF, unknown soil ph
Lights:
1x200w CFL @6500k, 1x150w HPS. Both are on 20/4
Age:
Auto(FFOF) is exactly 1 month old and starting to bloom, little nute burn on edges but shes doin fine.
DWC's are at 3 weeks
Air:
78-85F, 50RH, oscilating fan
Nutes:
For the DWC's, I introduced 1/4 strength dynagrow liquidgrow 2 weeks ago when I did their first rez change. They're up for a rez change TONIGHT, but I want some feedback before I change it in case I need to adjust anything. I was planning on doing half strength nutes this time (1 TSP per gallon) during this rez change, or should I do more? I have no other additives or nutes going in, just the dynagrow liquid grow.

A couple of the lower leaves have yellow spots. They look alright overall, but a few leaves in both DWC's are starting to look like they're getting them. I dont know if it was due to a recent high PH (they were both in the upper 7's until I brought it back down to 6 3 days ago) or if they need more nutes. Any advice please?!

The little Auto seems to be ok, the spots are appearing on the 2 hydro/DWC's.

haha man your plants are looking great. the tiny yellow spots are from a very slight ph fluctuation

Thanks for the help -- guess it was when the PH spiked to the upper 7's and I lowered it back down to 6. I'll go ahead with the rez change then. Should I change the nutes from 1/4 strength to 1/2 strength (1 TSP per gallon now for 1/2 strength), or should I go full strength (2 TSP per gallon) and see how they handle it? They're 3 weeks in, sooo I dunno.

if your doing everything right.... and ur still getting odd signs, its probably heat stress

I have some OG in dwc and they have the same spots, my ph, I think it was too low. I made some adjustments and have not seen any progression in the spots. I also have heat stress problems as well.

Yeah, I dont maybe it is heat stress too, i'm not sure what that looks like. My temps are around 85-88 during their absolute HIGH. This is with 2 lights in a small closet, and a small oscilating fan pulling air into the closet from the outside.

In the next few days I'm going to pull a AC duct in the lower part of the closet and then cut a hole in the wall and install a fan pulling the hot air out of the closet and into the open room outside. This way when I switch to flower I can make sure the closet stays closed to allow no light leaks and is still getting cold air from the AC and is exhausting the hot air from the lights. Hope that will take care of the heat issues.