ppm advice appreciated

Hey gang!

I've currently got a nice DWC/SCROG setup and am growing Williams Wonder and Chemdawg. I'm curious as to whether any of you gentleman or ladies know at which ppm these two particular strains thrive in DWC? It's my first time with both in DWC. I'm running GH Floranova Bloom, GH Liquid Koolbloom, Cal-Mag, and Bob''s Brew, ph@ 5.8, ppm @640 with two GH dual diaphram four way pumps going to 4 plants total. Currently things look great, but like every hydro crop I've time where PH fluctuates as does ppm from time to time. I'm one week in to budding.

I've done a multitude of searches and came up with 300ppm all the way up to 1300. I'd cry out loud if these girls died on me! Any advice would be greatly appreciated. Peace!

I'm trying to find out the same thing..When I started my dwc with clones (well rooted) i ran 400 ppm or so but had to back it off to 300 ( due to N burn) ...but now they are a month old and one foot high and a foot wide... some brown spots started appearing and yellowish leaves....I raised the ppm to around 650 or so two days ago and then went up to 920 today... there looking greener and much better already...I still have not changed water 16 gal res.. will soon.... The reason I'm going up is because the General Hydroponics Nute Calculator said i should be running about 1000-1300 ppm (www.General Hydroponics.com) and then go to the Nute calclator ........

Well hope it helps let me know if you find out