dealing with locked up Purple Kush leaf curl & nutrient burn, how long to flush?

Hello
I have been finding a lot of great information on this site. I am a fairly new (returning) indoor hydroponic grower using nutes from General Hydroponics Flora series on ebb & flow system. I have the air circulation, temp, & humidity under control using RO water ph at 5.6-6.0.
The problem is this is the first time for Purple Kush clones from Oaksterdam. My partner & I have read conflicting information about the amount of nutrient needed for these plants. Cervantes' Bible says they (indicas) need to be in hi range around 1100-1200 ppm. The PurpleKushseed site says 400-600 ppm range.These plants have been given around 1100 ppm.
Right now they are in second week of flowering 18" tall and locked up with severe leaf curl for about a week not growing.
They have been flushed out with low solution (50 ppm) several times separately (they are in baskets that can be removed from the table or buckets)and I dropped ppm to 436. I had Florasheild in the formula and read it can cause leaf curl so I took it out. Using Hygrozyme now also to help flush out. They don't seem to be responding and I'm wondering if I should just go to plain water flush and for how long?
I've flushed some with FloraKleen at low dose to see if that helps. We are running solution 8 times a day but have turned it off and skipped cycles when we flushed them.

My instincts say to remove all nutes and gradually re-introduce them but without already knowing the "correct" amount of nutes (if there is such a number) I'm not sure from where to start and of course we don't agree on what to do now that we screwed them up.
Any suggestions would be appreciated. I'm also wondering at what point do I have to conclude this may be a complete loss? Thank you for reading my post.
I will add pictures soon.
These pics were taken with my phone under the LED blue & red spectrum light and they came out all red so I adjusted the color.

Damnit, I'm having the same issues with my purple kush....I'm using technaflora's "recipe for sucess" and I'm pretty sure the curling and cupping is from too high an EC, and most specifically nitrogen toxicity. My EC was around 1150-1200 in 2nd week of flowering, but still using the veg formula. During veg I've been using pH down made from Nitric Acid, which to the plants is more nitrogen. So now into my 3rd week of flowering I've changed my rez to bloom formula, but made an aleteration to the formula; Instead of using Boost(3-0-2) and Bloom(1-4-7) at equal parts, I'm using 2:1 Bloom to Boost. I'm also now using pH down made from phosporic acid. It's only been a couple days and I can't say if it's worse, better, or the same. This is only the 2nd time I've grown the strain.

How did you resolve your issues?

Can you take a picture with out the LED on throwing off the color....Also how are your roots looking, post a pic of your roots. I would recommend you get or use ClearX for 24 hours and then start off with 50% of your last feeding and gradually raise with each res change. Monitor your PPMs when mixing nutes. It doesnt matter what feeding schedules say, let your plants tell you how to feed them. You really need to learn how to read your plants. Track all your feedings so when something does go wrong you can go back and re-adjust.

How are your res temps??? Air pumps on and good? Air stones good?

Peace

BKB