One thing that I did not see asked, but may have missed, is what reflective material are you using and do you move your plants around so different ones are in different positions to get better lighting at times?
I tend to want to say there is some form of burning going on but at least some of it could be cause by light bleaching do to uneven reflection. Using CFL’s would not normally give you temperatures of hot spots hot enough to actually burn but they can still bleach, or at least that is what I have read and not something I have experienced since I do not and will not use CFL’s.
I could not see it in the pictures so it may not be there but then it could be a lack of resolution or due to lighting when/where the pictures were taken but in the portions of the leaves that have turned white or fairly white do you still seen tiny green veins? If so you may have a magnesium deficiency. Normally that will show up on the lower portions of a plant first but it can show up at or near the top first at times.
As for the brown spots I do not believe that to be a mite problem. It can be any number of things but one of them can be a Zinc deficiency. That will cause plants to have spotting and bleached spots (chlorosis) between the veins first appears on the older leaves first, and then goes on to the immature leaves. That could explain both your spotting and your bleaching.
It will then start to slowly affect tips of growing points of the plants. When the zinc deficiency happens so suddenly, the spotting can appear to be the same symptoms to that of an iron and manganese, without the seeing the little leaf symptom.
Zinc is not mobile in plants so the symptoms will occur mainly in the newer growths. Having a plant that has a deficiency in Zinc can cause small crops, short shoots and have a cluster of small distorted leaves near the tips. Between the veins (Interveinal) yellowing is often combined with overall paleness. Pale or grayish, yellowing between the veins; rosetted weak is the signs of a Zinc deficiency.
With a low level of zinc in your plants, your yields will be dramatically reduced. Interveinal chlorosis is present in the small, narrow distorted leaves at the ends of really shortened shoots and the shortening between internodes. Leaf margins are often distorted or wrinkled. These nutrients will get locked out due to high pH: Zinc, Iron, and Manganese. These deficiencies will often occur together. Parts affected by a zinc deficiency are young leaves and petioles.
Having an excess of Zinc is very rare, but when it does happen it can cause wilting and in worse cases death. Since it is rare I doubt that to be your problem but the combination of both spotting and bleaching does make it possible.
If you have an ozone generator that can cause leaf spotting and that is often times confused with a Mg deficiency but by moving things around or turning off the ozone generator or repositioning it farther from the plants will clear things up.