pH or nuteburn? Please help, first DWC grow

Hey RIU

So, as in the title, this is my first DWC grow. I am an experienced soil grower, but due to my growing location ( super humid and in the tropics), DWC seemed like a fun experiment that may yield better than my outdoor stuff. So far, in my veg set up, the growth is phenomenal, a, all of roots are super healthy (thanks to heisenbergs tea). I am using 5 gal buckets, in a 3x3x6 grow area, 400w HPS, 6 in inline fan and one ossilating fan. I am using Dyna Gro --> Foliage Pro Formula, Pro Tek, Mag Bro and Bloom.

So my issue is arising out of my NL #5 ( Nirvana strain). I stopped feeding her N-strong nutes about two weeks ago, and no signs of burning or over N toxicity seemed to be occuring. However, over the last week and a half I'd say, since I switched to full bloom. This is when the issues seemed came to the surface, and a majority of the top fan leaves and small bud leaves are curling down like a mofo. The fan leaves are also very dark green, which makes me think it is N toxicity, but if I cut out N over two weeks ago, shouldn't it have cleared out a majority of it out of its system. My bloom formula is 3-12-6. So, N should be negligible.

I have been very diligent watching water temps, pH and ppm ( on .7 scale). So, I am feeding this NL #5 @ roughly 200-230 ppm ( a slow gradual increase over the last 10 days). My ppm of my tap water is about 30 ppm, so I am feeding roughly 200 ppm of nutes.
I know this seems "low" to alot of people, but I am running a grape god right next to her, and I have maxed my feeding at 400-500 ppm, if I am getting great results at this level, I have no idea why people feed at 1000+ ppms. Just kinda boggles me.
I have attached some pics her. Thanks for your help

DWC is extremely difficult technique to use to get good results when growing marijuana. I recommend using an antibiotic such as SM-90 to keep your roots healthy as well as an enzyme such as Hygrozyme or Cannazym. Temperature is key if your water gets above 75 degrees that's when your plants can risk growing pythiums SM-90 will help prevent this. I would also be using some air stones in each bucket to supply some dissolved oxygen into the water. It doesn't look like a Nitrogen burn to me because it's not effecting the entire plant. When your plant is suffering from a Nitrogen toxicity every single leaf from top to bottom will start to curl downward like some of yours are. It looks more like lock outs caused by too much Phosphorus. The mag-pro you are using and the bloom formula both have high amounts of Phosphorus. Too much Phosphorus can block Copper from being absorbed and Copper can distort upper younger leaves without any necrosis occurring. Perhaps switching from mag-pro to a Botanicare's sweet which would replace the magnesium and sulfur that the mag pro was giving you without adding any Phosphorous.

Thanks man! This info was great!
So would you recommend us emptying the 5 gal bucket, and maybe just leave regular ph'd water for 24 hours, and then re-add the Bloom with the botanicare sweet? or should just run bloom for a bit?