Your plant will recover and do well!
How about you get and read a book about growing.
Try this one by Ed.
http://www.amazon.com/Marijuana-Growers-Handbook-Complete-Cultivation/dp/0932551467
Now then, did you read it? GREAT!
Now you won't need people giving you the wrong answers to hold your hand!
I looked at your first pic and I GAUR-AN-FUCKIN-TEE you had NO problems with that plant until you followed some BS advice!
The wash was the start.
The bottom leaves in that first picture died off from NATURAL causes. (old,shaded,unneeded. The plant used the nutrition IN the leaves as they died off)
Let your tap water sit over night and it'll be fine to use. You don't NEED to use RO! Dude! CALM down! Stick your finger in the soil down to your first knuckle. Does it feel dry? Then water. Does it feel wet? Then don't water yet!
To SKI......yeah buddy, why don't YOU post a few pics of your 6ft tall plant under a 400w hps...With NO yellowing/die off of lower/no longer used by the plant leaves(because the light won't penetrate that far any more)...I would love to see that!
This thread is a PERFECT example of why many of us simply sit on the fence and be entertained by the wanna bee's jumping in with the answers to questions by overly worried "newbies". I gave you the real answer the first time, I stick to that! PERIOD! Your plant was FINE! the lower leaf die-off was natural!