400w lighting question

[uhuru]

I'm planning on using a single ended 400w 20k bulb to light a 30x30x18 cube. Would I get enough fluorescence out of my SPS corals with an HQI ballast or should I use an electronic ballast so I can get more blue? Will I need to supplement with T5's? Will my corals be able to grow under this light? Thanks! If anyone has pics showing what a similar setup looks like that would be great.

[Michael7979]

I run a 20k Radium off HQI ballast and really like it, (sorry no pictures). But I run VHO's before and after to help and to ease the run time on my MH's.

[chewie]

Actinics are up to you. You won't NEED them, but you may want them. If you use a good reflector (lumenarc III) you can cover the whole spread with just the 1 bulb.

 

As for the HQI vs. regular ballast, You will get a little better growth running the 20k's off of the HQI but you will be replacing the bulb more often. I've ran radiums, ushio, PFO, and XM off of the HQI and I was changing bulbs around the 8-9 month mark.

 

Look into the M135 pulse start ballast if you're worried about changing out your bulb too often. I run a 400w ushio 10k off of a PFO pulse start and the color/intensity is great.

 

The 20k/HQI combo is hard to beat for color though.

 

Whatever you do, don't skimp on the reflector.

[andy]

I've only run 10K bulbs myself, but I've read that you'll see reduced coral growth under 20K bulbs. If true, this is a real bummer 'cause I like the look of 20K Radiums but love the growth I'm getting since upgrading to 250W 10Ks.