I have a 400 watt metal halide on a 90 gallon corner style aquarium. I have
the choice of a 20K or 10K bulb. Wondering which one is the best for a
planted tank with Discus.

I have a smaller tank with 10K pc bulbs and that tank is doing fine. I was
just wondering if a 400 watt metal halide is too much for a plant tank.

Thanks,
John