best hid's for plant growth

[Steve]

What are the best hid's for plant growth. Most supplyers over here recommend Sodium which I have been using without much success. I keep getting told that my plants need more light: I'm no expert, but the plants which I am growing do not need 30,000 lux. I feel that they would grow much better under metal halide lamps, but I am reluctant to spend any more money until I am sure. I have already bought 250, 400, 600 watt systems on the advice of 'experts' in the UK.
Steve