Ok when I didn't know better,I used tap water (350ppm)coming out of the tap,I always had my 2 meters (ph and tds)5.0 to 6.0,used the same food,One thing I noticed(with this grow)is when I checked the ph in the bucket,it fluctuated badly.When I took a sample of the res water that's when I got an accurate reading.Now it's different since I have switched to ro water with the cal-mag.Now I am able to take accurate readings straight from the res.My 400 watt MH is about 10 in away from the top of the tallest plant.I know that you said that the different ages concerned you but a couple of the "newest" plants are bigger than the "old" ones.The mix that I have going on now was changed 2 days ago because I didn't know about cal-mag,So I decided to start over fresh.So I haven't added any water yet,When I decide to add water it will be ph'ed ro water without cal-mag.My room that I use does not have fresh air,So I keep the door opened a lot.It's about 85 to 90 degrees in here with the door closed for 10 hrs.3 fans blowing at all times.The only difference between this grow and the last one is (1) The Water (2)the different age of the plants.2 plants are about 3 weeks older than their 7 sisters but you couldn't tell by looking at a couple of them.I will post a pic with the plants numbered and maybe that'll help us out more.Thank God for the internet.And thank you guys for taking the time to help me figure out this problem