Quote Originally Posted by polishpollack
EC and ppm are basically the same. They will each give you an idea of how much fert is in the water. You're right about conductivity and ppm is parts per million. I don't know what a good EC numbers are like but ppm range is usually 500-750 when their small and up to 1500 when their big. You add fert to keep close to those numbers throughout the grow. I'd paint the lid black if I were you, but that's container's wrong. If you do this right, 8 plants will quickly outgrow such a small container. For 8 plants you can use 5 gallon buckets seperately or put two or three plants in large tubs. 8 plants done right in DWC can easily take over a small bedroom if done right. But you've go to do it right, use the right fert, don't overdo the nutes, average temp 75F, give airflow, lots of air to the water with your pumps. Best of luck. Any questions, just ask.
I should definitely get a ppm tester.. It will show me if I am adding up the nutes right or not.. I was not planning on growing on 8 plants at the time as you said the container is too small for 8 plants. I think I will go with 3.
My system is more of a EBB and Flow system right ?
How do you think I should set up the lights for 3 plants ? ( knowing that i have 3MH 150w and 3 HPS 150w). Let me know what would you do in my case ? And how far should I keep the lights from the plants ?

Sorry for all the questions and I appreciate your inputs ! Thanks.