Well nice set up bro... two 600's is a great combo a hell alot better then a 1000...
And a water chiller is great but expensive...
AN nutes are great too...
My friend floods his 4 times a day in veg for 15 minutes, then I believe 30 minutes 3 times a day for flower...
Let me get right back on the ppm's
I don't use a ppm meter so I have no idea... But I will get a good answer for you today or tomorrow,,,
What are you using for a medium? coco or grow rock or rockwool?
You might also wanna cut a hole it your mat where the drain is.. I have heard your roots can clogg up the drain. And also don't ever move your pots once they are on that mat.. Because your roots are suppose to grow into the mat...
so if you have faster flowering strains put them on the outside and the slower one leave in the middle..
Also if possible buy some go gnats... they tend to be a big problem on tables...
I got a few ?'s...Im growing with: 2-600w HPS air cooled in a Dark Room tent, flood and drain 4x4 table w-70 gal res. 3-6" inline fans(1-for intake,1-for exaust cooling both lights,and 1-air movement) Grow-Micro-Bloom from A.N. My medium is 6" rockwool blocks on a coco fiber 1" grow matt. My table floods for 15mins 3x's a day while the lights are on. I should be getting my water chiller tomorrow for tha res. My room temp are 72.5 F and 60F @ night. how long should I be flooding for and how many x's a day? Im currently growing purple urkle clones. what should my ppm's be for the first 2 weeks of flowering? Why are my clones drooping? My guess is probably too much water what do you thing?