Metal Halide - Choices

[fkshiu]

Joe, it depends on what you want your tank to be. I get fine coverage and grow all sorts of high light stuff with 2x175W Vertex electronics running Iwasaki 15Ks under Lumenmax pendants. PPFD per watt, this is the most efficient set up according to Sanjay's figures using less electricity than 150W HQI system but putting out more PAR than some 250W systems:

http://www.canreef.com/vbulletin/showthread.php?t=59449

Understand that I have a mixed reef with lower light creatures too and my tank is on the shallow side for a 6-footer. Looks wise no one has ever noticed any dim spots. If you want a full out SPS garden, however, going with three 250W pendants is the better choice. You start getting diminshing rates of return once you hit 400W territory.

You can have a closer look when you come by for you macro later this week.

[Myka]

Those Iwasaki bulbs on electronic ballasts are a PAR breaker...not typical! You can't get the same PAR using different bulbs on that ballast. As long as someone is happy to commit to that one single bulb, that's a great choice! Pricey bulb though...

[Myka]

Originally Posted by plutoniumJoe

What I am reading in the article though states that you get more light for less power out of two 400 vs 3 @ 250.

Keeping in mind I didn't even glance at the article, what I think they mean is that you get more intensity out of the 400w bulbs than you do out of the 250w bulbs. You use 50 watts more using 2x400w than 3x250w, but the intensity you get out of the 400w bulbs makes up for that. So essentially if you get more intensity for close to the same amount of electricity, the efficiency is greater using the 400w bulbs.

Having said that, I still think you're better off keeping 3x250w over a 6' tank unless you get some sort of custom reflector for 2x400w that spreads the light over the 6' length, but doesn't spread it past the width of the tank. Now that would be interesting...

[lastlight]

Sorry I wasn't thinking specific ballast data you used generic numbers so I thought I was missing something. My radium is a 250w and burns at around 333w so I fully get that. I always thought the e-ballast would use a little less. For example my same Radium on icecap uses 244W. Not sure if this was the old or newer icecap but I didn't think any e-ballasts overdrove bulbs.