I don't know a whole lot about light, but 400W is already a good amount of light, and you can bloom everything (I assume) under it. But 1000W?
That's alot of light! The low/medium light orchids will not tolerate it (unless they are very far away from the light), and you will have to deal with the extra heat generated by the lamp, not to mention the increased electric bill! It's the hps which produce light more in the red, favoring blooms. Blue will tend to favor growth more.
Personally I would stick with the 400w and possibly add (or even replace) another light with a higher color temperature (more in the blue end of the spectrum) to promote growth. A balanced light will be around 5000k, same as daylight.
How long are you leaving the lights on? What distance from the plants?
Feel free to correct me if anyone thinks I'm wrong! Like I said, this is just my
!