Metal Halide bulb cuts off and on

[Engloid]

I have one of the 6ft Coralife fixtures, with three 250w metal halides in it. The last couple weeks, I have had problems with one of them. Periodically, it will turn off. I can leave it alone and it will eventually come back on.

These have the big box-like ballasts, one for each bulb. When I got this fixture, I knew that heat was the major killer of them, and the boxes would get so hot you couldn't leave your hand on them....so I put some 110v case fans into two of them. I wired them in so they come on when the lights are on. The third, I didn't put a fan in yet. Two reasons I didn't do the third...so I could see what difference it made (comparison), and because I was worn out that night and didn't want to get into the third.

The fans are a success. the boxes are not even warm now. I know they say not to stack them, but since they are cool, I did it anyway. The one without a fan is in the middle, and is much cooler than it was before, just because it has cooled ballasts on top and bottom of it. I had thought that maybe the ballast was getting hot and shutting down, then as it cooled down it would start up again. However, the ballast that runs the light that's cutting off is one that has a fan and always stays cool.

What other things should I check? I know it could be a short...but I want to know what other things it could be so if I tear into it, I can check them all at once.

 

[Reefing Madness]

Bad ballast. Put it on the side by itself, making sure all the wires are connected and not crimped. Ballasts are usually the reason the light comes on and off.

 

[Engloid]

Bad ballast. Put it on the side by itself, making sure all the wires are connected and not crimped. Ballasts are usually the reason the light comes on and off.

Any other things it could be?

What options do I have if it is a bad ballast? Im assuming the major component cant be repaired. Can i even buy it? Can I replace it alone or is the cost not worth it? Can I replace the one ballast with an electronic ballast? Any specs I need to know to choose one or will any 250w ballast work?

 

[Reefing Madness]

I've changed my ballasts out a few times. Not a big deal. Double ended ballasts are easy to find. You want to make sure it is indeed the ballast first, so change that bulb with one of the others. If it does the same thing, just get another ballast.
Cost is another thing, they will coast a bit, but that just comes with having them. All depends on what you consider to much.
250W Metal Halide MH HQI Electronic Ballast 110V 240V Standard Aquarium Light | eBay
250watt Dimmable Electronic Ballast- Coralvue

 

[Engloid]

I think the ones I have now are magnetic. Electronic runs cooler if I remember right.. ? Any other advantages?

 

[Reefing Madness]

Other advantages, no I really don't think so. Sorry, I just assumed they were electronic.
Aqua Medic 250W Reeflex Cube HQI Metal Halide Ballast Live Coral Made in USA | eBay

 

[jonny]

I think the ones I have now are magnetic. Electronic runs cooler if I remember right.. ? Any other advantages?

I think they use just a bit less power, usually are smaller, and they don't make any type of humming noise..I have the ballasts from the first post, and they are just fine..they power up my phoenix 14k s with no problem, they get hot, but not so hot you can't leave your hand on them...