No spots on undersides. Two plants are side by side and only spots on one plant so I feel any bugs would be on both. It seemed to only affect the top 3 leaf tiers all around and only the fans none of the smaller leaves.
Spots on leaves?
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Muddy
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Okay, if no bugs let's look at your pH. I see you are feeding at 7 and getting run off of 6.2. That indicates that your actual soil pH is somewhere around 5.5, which is too low. What you're seeing could be the beginnings of a pH related nutrient lockout, specifically magnesium. As you can see on this chart, at that pH most of your major elements are unavailable to the plant.
Since you are in a 3 gallon pot I would suggest you mix 3 tablespoons of dolomite lime into the top layer of your soil before you feed them the next time. Dolomite will bring your pH up but it takes about 2 weeks to become effective. In the mean time mix 1 teaspoon of Epsom salt to a quart of water and mist both sides of your leaves once a day for about 3 days. That will help get some magnesium to the plant while the lime is become effective.
I would also suggest you ditch the Miracle Grow soil for your next grow. Most MG soils besides containing the water retention polymers also contain slow release nutrients. Both of these are known to cause problems when growing autos.
Since you are in a 3 gallon pot I would suggest you mix 3 tablespoons of dolomite lime into the top layer of your soil before you feed them the next time. Dolomite will bring your pH up but it takes about 2 weeks to become effective. In the mean time mix 1 teaspoon of Epsom salt to a quart of water and mist both sides of your leaves once a day for about 3 days. That will help get some magnesium to the plant while the lime is become effective.
I would also suggest you ditch the Miracle Grow soil for your next grow. Most MG soils besides containing the water retention polymers also contain slow release nutrients. Both of these are known to cause problems when growing autos.
A couple times I've had white/cream colored spots on leaves. It looked more like loss of pigment or bleaching. That was under t5, so I don't think it was bleaching. The only thing I found that was even close to it was this page about ph fluctuation. (<<link)
I haven't seen that in other lists of deficiencies. I don't know if that means it's not widely recognized, or if the above link misidentifies it. But... the photos at that site look exactly like what I had.
Yours look more speckled like the beginning of calcium deficiency. Mine were larger squarish shaped blotches. Like entire cells on the leaf lost their pigment.
I just wanted to throw that out there in case you see a resemblance. It doesn't seemed to be widely recognized as a symptom.
Thanks guys. The ph runoff after the flush was 6.6 roughly..I'm using test strips and really need a meter. I wasn't planning on even following this grow thru so I threw it in the MG against my better judgment. I knew the show release ferts would become an issue eventually. Oh well..did I mention I love a good challenge? 
Muddy
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Flushing does stress the plants and should only be done as a last resort. I wouldn't flush them but keep feeding at pH 7, add the lime and continue to monitor your run off. When you see it start to rise, then lower the pH of your feeds accordingly until you are getting run off that closely matches the pH of your feeds.
Here's the soil test from today, first one since flush last week. To me it looks like low- to mid 6. I added a small amount of lime to the top layer of soil and fed as normal with nutes at ph7. And guess what...runoff is at roughly 6.5. So I think it's the slow release ferts dropping the ph on the way down..?
