Okay so of all the suggestions the easiest thing for me to try was to make sure the bracket was flush, and holding the bulb evenly.  So I didn't take all of Silcox's advise, but here is what I did.  One night, I just wiggled the sockets around.  Thinking maybe this will ensure that the bulb really is seated well with the springs.

Well for 4 days in a row now, when the timer clicks on, the bulb fires right up. So, I guess once in a while it is a good idea to wiggle them connectors, and make sure the bulb is held in well.

SILCOX-     ding*
(hope the large font catches your eye)

Adam

wsinbad1 wrote: Thanks to Eric who went out of his way to make sure that I had a working setup.  I've even heard from him several times by PM checking up to make sure I was happy with my purchase.  Eric and Arjen at Marine Aquatics have been extreamly helpful with the upgrades I have been doing on my tank and are much more worried about my satisfaction than selling me on something.

I'll second that.

Adam

Looks like I got here late, but here's my story..

I have 2 250 HQI 20K bulbs on my tank.  They are fairly new and are run by electronic hellolights ballasts.  When first set up everything worked great.  After a couple days I noticed that 1 light was no longer coming on and the ballast was making a buzzing noise.  I got these setups from Eric and when I talked to him he told me to bring it in and he'd take a look at it.  He was ready to swap the ballast out and give me another, but decided to try the "new" one before he gave it to me.  What do you know?  Same problem.  So he sent them both back to hellolights for new ones.  The new one fired the bulb when I was at his store so I took it home, plugged it in and it didn't work.  Changed some wiring and it worked.  Great!  Tried again 10 minutes later and nothing.  Changed some more wiring and nothing.  This went on for about an hour.  Finally I change the "bad" ballast with the "good" ballast and the "bad" one worked and the "good" one worked.  So I left everything alone.

Several days later as I was sitting by the tank the timer clicked over and one light came on and 1 didn't.  The 1 ballast was buzzing again in the corner.  So this time I swapped the bulbs in their fixtures.  Sure enough the problem followed the bulb.  After messing with the "bad" one again for 30 minutes I finally gave up and decided to leave the ballast plugged in and let it buzz.  (The buzzing by the was is the ballast trying to fire the bulb.  Eric tells me that it will only try for 10 minute and then quit.)  Anyway, I left the room and came back 2 minutes later to find the bulb on.

So!!! Long story short it is most likely your bulb.  It seems that leaving the ballast to continue to try firing the bulb will usually eventually light the bulb.  Mine has always come on, I just don't know how long it takes each time.  Doesn't seem to be hours though.

P.S. Thanks to Eric who went out of his way to make sure that I had a working setup.  I've even heard from him several times by PM checking up to make sure I was happy with my purchase.  Eric and Arjen at Marine Aquatics have been extreamly helpful with the upgrades I have been doing on my tank and are much more worried about my satisfaction than selling me on something.

Sure there are core and coil ballasts for HQI (they actually run the bulbs at a higher output then electronics), but they don't have any sensing circuit that I'm aware of.  They are just like pulse start ballasts (core/coil, run capacitor and starting ignitor) as far as I know.  Let us know what you find.  Sorry, this isn't really helping Adam too much .

Oh... wait.  Are you thinking about the differences between probe start and pulse start bulbs?  It's true that bulbs designed specifically for pulse start ballasts can have better spectral retention then probe start bulbs, but that is because of the metal halides within the bulb not the ballast.  The gases in the pulse start bulbs are presurized more then the probe start bulbs.  This "feature" is available whether you use a core/coil or electronic ballast.  And this really applies to commerical bulbs.  I'm not really sure it applies to aquarium bulbs (i.e. most people change out their 175w Ushios (pulse start) as often as their 250w Ushios (probe start).  But I could be wrong regarding the aquarium bulbs, I know at least one guy who claims to get better spectral retention on his 250w Ushios using a pulse start ballast instead of a probe... but it's only antidotal evidence.

Well usually yes, I would mean electronic. But there are magnetic/tar ballasts that produce the correct voltage requirements specific to run HQI/DE bulbs, so wouldnt they fall in the same category?

But from the sounds of it it seems like the "color shift" thing may be a totally different thing completely. I will see if I can do some research on that.

You mean electronic ballast not HQI don't you? 

Maybe all electronics do, but I seem to recall reading something about a month ago about the Helios ballast doing something "special" with regard to color shift.  At least I think it was Helios... 

jfinch wrote: Is this the ballast that will adjust voltage to the bulb to maintain color specrum?

Isn't that the benefit of HQI ballasts? I thought they all did that...

Sorry I don't know anything about the Helios ballast.  It must be a fairly new product from Helios?  Is this the ballast that will adjust voltage to the bulb to maintain color specrum?