PLEASE HELP! leaves turing silver and yellow..unsure what the cause?

1) started as white powdery substance on side of rockwool cubes
2) next the leaves started to turn silver
3) now some leaves near the bottom are turning yellow and dying

I changed the nutrients to include 5.5 ml (aquaflakes A&B), root excelerator, liquid karma, and multi zen. switched from MH lamp to fluorescent, increased air flow, tried spraying the leaves with 1:9 skim milk soln and 1:4 hydrogen peroxide...I am going to try baking soda tomorrow. Nothing has worked. does anyone know what this can be? this is first grow could really use some feedback. these are zambezi autoflower strains
Is this a nutrient or pest problem? Mildew?
View attachment 3021088View attachment 3021093View attachment 3021095

Powdery Mildew

It's that time of year again.

should i remove all the infected leaves? pretty much all the leaves are infected this might kill the plant?
this is what i ordered:
http://www.amazon.com/gp/product/B001EJKXEO/ref=ox_sc_act_title_3?ie=UTF8&psc=1&smid=A19I28AKMOKQVB

will try baking soda tomorrow

If you can address the conditions that make your plants an attractive place to grow for PM you can probably save them in conjunction with a treatment. But you really have to start by looking at things like lowering humidity, getting good air flow, spreading your plants out, even pruning a bit if leaves are in contact with other leaves, etc... But that looks pretty bad with the amount on the rockwool cubes. Might look into renting/making/buying a sulfur burner after making all the environmental changes you can.

Be careful using baking soda, I almost killed a couple plants with it. Not more than 1/2 tsp per quart, and add a wetting agent. It needs to be washed off the plant not long after applying. It is highly alkaline and MJ doesn't tolerate it well.

There are many other products I would use instead. Im no expert on PM, just giving fair warning on baking soda.
Sablezen gave good advice, focus on the environment.