Never mind, answered my own question... anyone who wants to know, see this thread:

http://www.reefcentral.com/forums/sh...icecap+ballast

You can run any bulb which is rated for the nominal wattage of an electronic ballast. In other words, a 250W e-ballast can run all 250W MH bulbs. The downside to an e-ballast is that it will generally produce less PAR than a comparable magnetic ballast with the same bulb.

With respect to the OP's original question of 175MH, the best combination for maximum PAR is a 175W electronic ballast with the Iwasaki 15,000K bulb. This combo will give you as much PAR as many 250W combos while using less electricity than a 150W HQI system.

It's all a balance between looks (which is subjective), PAR output and electrical usage.

The best place to look up actual objective measured PAR values along with actual electrical draw is Dr. Sanjay Joshi's lighting guide:

http://www.manhattanreefs.com/lighting

Just pick your bulb and/or ballast and it'll spit out all the information you'll need in the PPFD (PAR) and Watts columns.

HL649, I Ran 2 250w XM 20k Mogul Bulbs on my 75G. I build my own xfmr using a probe start ballast. Worked like a damn. I still use the XM20k on my SPS tank and they grow well under that light.

If need be, you could always raise the lights from the top of the tank. That's what I had to do. It can be a bit of trial and error.. My current tank is 20" deep and my lights (250w 14K DE HQI) sit about 12 inches off the water's surface. That height seems to be just right for my SPS that are on rock work and my LPS'/zoos that are on the sandbed. I like the added bonus of having virtually no salt creep on my lights which I always hated when I had my lights lower. I haven't really heard from anyone who was overly disappointed with either light technology.

I'm a total halide fanatic, but I wouldn't run halides on an LPS tank. Too much light, plus you pay only a little less for a 150w or 175w halide bulb as you do for the higher wattages, so it just seems a waste. If I decided to make my tank LPS dominant again I would sell my halides and get T5s. I had an LPS tank recently that ran very well for 2 1/2 years with T5s. Most people would be surprised how little light LPS need in order to thrive. Many people over light them, and when they cut back lighting they experience much brighter colors. Besides, the T5 bulb choices give you lots of options for "color cheating". :D

my opinion
 

HQI double ended all the way!

I'll take DE over SE any day too! :D

this is kind of a grey area, MH is not to much light for LPS, but if you were using T5's for a long time they will take a while to adjust. look at the reef around austrailia and haiwii, there are LPS in 5 feet of water which are reciving more PAR than we could ever dream of putting in our tanks. the problem is most people don't have enough flow in there tanks to prevent/minimize bleaching. I have done exparaments after reading a few articles on bleaching and water flow and which a low flow rate of 20X turnover I could bleach the heck out of frags, but when I increased the flowrate to 120X I couldn't get them to bleach at all with all other conditions being the same.

now just increading pumps isn't enough, the trick is to spread the flow out all over so it ends up being a gentle current not a jet wash, I had a 94 gal tank with almost 12000 gph flowing in the display, but you could put your hand anywhere and all you felt was a gentle flow.. it took me about a week of screwing around with placment and such and I don't think you would ever acheive this with a sand bed (as the flow on the bottom of my tank was the same as the middle and the top) and you may have to be willing to rearange your rock to give you the best flow not the best look, but you could probable achieve both with a little more paitents than I have :biggrin:

Steve

If I am right in assuming you mean "DE over SE any day", then my question is why?

Grrr...I just replied, and managed to lose it. :twised:

Basically, I prefer the look of DE over SE. When I comment on someone's tank "Nice lighting", 9 times out of 10 it's DE powered by electronic ballasts. I also like the spotlight effect of DE which makes coral placement easier.

This is interesting. I have always struggled to get high flow without blasting spots, but I don't have the patience to mess around with it for very long, and I never seem to get anywhere anyway. I know my LPS are PO'd about my Wavebox, and it's been at least 4 weeks since I installed it, so you would think they would be used to it by now...??