20K for Seagrass?

[monicaswizzle]

Friends--

Well, my shipment of plants (shoal and manatee grasses) has arrived and I am about to plant. Per my earlier email, I am planting a 75 gallon tank that currently has 130 watts of PC light on one half and Normal Output lights on the other half. I decided to upgrade my lighting since folks advised it is marginal for the grasses. I will keep the PC light on one half, but I will replace the NO light side with a 400W Metal Halide. The fixture that I ordered comes "complete" with a 20,000K spectrum light. From what I read 6,500 is more ideal for seagrass. So, should I rush out and buy a 6500K bulb, or will 20,000K be "plenty good" for a few months and just go to 6500K when it is time to change the bulb? For what it is worth, the PC side will continue to have 7500K and blue actinic, both in 65Watts.

Thanks for your opinions! I will let you know how the planting goes.

[graveyardworm]

400 watts is a ton of light for a 75g. The spectrum is going to be off from what the seagrasses would prefer, but I think 400 watts of any light would probably be sufficient. 10k would probably be my choice to maintain nice visual aesthetics and provide the plants with close to the correct spectrum.

[monicaswizzle]

Thanks David. I figured that with 400W I could afford to miss the ideal spectrum fo a while.