It's a weed how could I F##K it up!!!!

I first noticed that the plants started to have VERY slow growth and were turning light yellow starting at the bottom with the tips of the leaves dying and they are droopy with no change after watering, then a couple of weeks later some of the plants started to develop small brown spots on the leaves.
Using a drip irragation setup, water 4 times a day for five minutes. I place cloans in 1" rockwool cubes then when there rooted I place them in 4" net pots with hydroton. The plants are in the veg stage have been in the room for 6 weeks and there around 6" to 10" tall. I keep the PH at 5.5 to 6.0 I have the PPM at 600 I check this using a Hanna electronic meter, since I've been having problems I have recalibrated it many times. I change the water in the reservior every 3 weeks using RO filtered water keep it at 70 degrees. Using Technaflora B.C. hydroponic nutrients I mix in the B.C. boost first using a 2 to 1 ratio use Advanced nutrients PH adjusters. running 1 1000w HID about 2 feet from the plant tops at 18on 6 off, day temp 75 night 65, have lots of fresh air flow. Have inspected for bugs and found none. I am thinking possiable Nitrogen deficiency based on other posts but not sure.

looks like its time to up that ppm im using bc nutes. my plants are much smaller and i already have my ppm up to 750. id say bump it up to 800, and if they dont show any negative signs move up to 1000. you should be at full recomended veg dosage by now wich is 1200 i think. you could probably even push it a lil further than that too.

by the waymy plants are 3 weeks old at 750 ppm. and they are short but have many tight spaced nodes. much closer than yours. they are dark green and very healthy looking. only one of my plants is showing slight burn but the others are loving it so shes got to deal with it lol. shes actually starting to adjust and is looking much better today after i just checked. your plant is starving dude feed her.

Thanks for the reply, I had no idea I should have the PPM up that high, will make the adjustment ASAP glad there is some where I can go for help thanks a lot!

no problem man. good luck.

also make sure your ph is right, so you dont get nute lockout. fluctuating between 5.5-6.5 is fine. if not better because different nutrients are available at differnt phs.