major leaf yellowing

This is my first posting or thread on what looks to be a great resource with my NEW indoor gardening project. I am hoping to get a little advice before going off the deep end on a tangent where i am not certain which direction to go. Here is a overview of where I am at.
I am beginning the fifth week of my flowering stage and up until this point, I will not say flawless, but things have been going VERY well. I have been experiencing extreme yellowing of the large mature leaves, but nothing like where I'm at today. I use General Hydro nutrients (3 part with supplements on chart), and yesterday I changed my solution. This is the third nutrient solution change in my bloom stage, and I have been using the chart for amounts to the letter. I started with the "transition" mix, went to the "bloom" mix, and yesterday went to the "aggressive bloom" quantities on the chart. Like I said I have been experiencing extreme yellowing of the large mature leaves, and some small yellow "spots" on one plant, but nothing that seemed to be alarming until now. Now it seems as ALL the leaf edges and tips are yellowing at a much greater pace (it has only been one day) since nutient solution change, and the yellowing seems to be spreading into the newer smaller leaves also. When changing I flushed system out with clear filtered water with a ph of 5.7/5.8 for a few hours and then drained and added new mixture. The yellowing seems to be advancing at a pace I now find alarming and want to do SOMETHING, but would like some advice before proceeding.
From research I have been doing, it appears I may have a MG, or MH deficiency, but my inclination is that I may be OVER FERTILIZING, and I should flush the system and reduce nutes to the "normal" bloom level. Although I was having the yellowing condition before , just NOT to this extent. This is my first thread and post, so I will need to figure out how to post photos if that will help. I feel I need to do something ASAP, and would appreciate ANY thoughts or opinions before jumping into anything.
Thanks in advance,
corvettechronic

BTW-DWC system in 5 gal. buckets under 600w HPS, ph at 5.7/5.8, with eexcellent ventilation

Hoping for some input, chomping at the bit to do something. Here are a couple of photos

to me it seems like your over doing the nuts. or your ph is of. try recalaibrating your meter befor testing it. on another note your into week 5 so its okay cause your going to want it to absorb as much nuts as it can befor you flush it for the last two weeks. whats the strain and flowering time?

I have a stick, a moniter, and a meter (new) all checking within .2 of each other at 5.7-6.0. Strains are Dairy Queen, and Purple Kush. I have them on timer with 12/12 cycle.

i mean how many weeks for that is average flowering time. like 7-8weeks?
have you done anything new since your post?

them shits need like 9 weeks

that kinda yellowing is so classic i forget what it is....cal/mag def?

hopeflly u got a PPM meter and that shit is up to like 800

What I do when this happens (yellowing) is that I systematically go through the basics; check water, ph balance, nutrients, temp, humidity, pest, and then I try to remember if I did anything different or has something else occurred within the last 72 hours that may be causing the yellowing. I invested in good quality growing equipment to help with with my growing since in the beginning I like you was playing the guessing game. I hate guessing! I like to know so that I can accurately correct the problem right away. Do you have equipment that can check for factors that may be contributing to the problem of yellowing? Or are you just observing the symptoms and hoping it may or may not be one of the many things that could be wrong? It really depends! That is why equipments is so important. I learned the hard way.