[ryddo]

I know they are usually hot, but this is crazy. Here is the situation. I have just converted a PFO lighting fixture from a dual 175W SE halide to a dual 250W HQI fixture with 2 10k Reeflux bulbs and 2 250W Coralvue ballasts. The problem that I am experiencing is that one bulb is fairly cool when running but the other is extremely HOT! When I say hot, I mean that touching the light fixure is painful?? Has anyone ever had this issue before? I wired both HQI sockets exactly the same and the ballasts are identical? Please help!

Thanks,
Ryan

[charlie]

So you are using DE bulbs in there now? For the life of me, I don't know why you would have this problem. Is one bulb closer to the fixture?? Are the fans working? Maybe someone else could chip in here with an idea, unless you may have a bad bulb.

[ryddo]

This is really driving me nuts. They are both in the identical locations in the fixture, one on each end. In the 6.5 hours that i have the lights on they are raising the tank temp almost 10 degrees. Both fans are working, one blowing in and the other blowing out. Maybe i should have them both blowing in?? The light that is cooler has the fan blowing in? Just a thought. If the bulb were bad, do you really think that it being hotter would be a result? This is crazy.

[charlie]

Are you absolutely sure that each bulb is a 250W? I know that is a dumb question, but I have seen stranger things happen. It sounds as tho the bulb is being overdriven!!! That is just a guess.

How close is this fixture to the tank, raising the temp that much is crazy.

[ryddo]

I will have to check the bulb tonight! i never thought of that. One other thing. When I walked in the house last night it smelled kind of wierd, I never thought that it might have been the light fixture. This morning I was looking things over and just happened to look in the fixture through the fan opening. Holy crap! One of the Current USA moon lights that I installed had actually melted due to the heat!!!! That is not right! Needless to say I have disconnected both lights and tonight I am going to really look things over!

Ryan

[Ninong]

If it's a double-ended metal halide lamp and it fits in the 250w sockets, then it's a 250w lamp. The 150w DE lamps are smaller and the newer 400w DE lamps are larger. Only the 250w size fits in 250w sockets.

I ran an Aqua-Medic Aquastarlight Future fixture with two 250w 10,000K HQI DE lamps and a 25w blue incandescent lamp in the middle. It had onboard magnetic ballasts and I can tell you that within ten minutes after the fixture was on, you couldn't touch the top of the housing with your hand. OK, you could touch it for a fraction of a second but you couldn't hold your hand on it.

I once accidentally bumped the top of my right hand against the 3/16" thick tempered glass UV shield on the bottom of the fixture and I got a very nasty burn. My hand was even wet at the time and the contact was for just a fraction of a second. It was worse than accidentally touching an oven rack when the oven is at 450 degrees. Yep, I've done both! It took about a month to heal completely.

I believe the operating temperature of the inner glass bulb in a 250w double-ended metal halide lamp is approximately 3,000 degrees Fahrenheit. I have no idea how that compares to single-ended metal halide lamps because I don't recall seeing that same information on them.

I talked to the Aqua-Medic rep once about why they couldn't use electronic ballasts onboard in their fixtures and he told me it was because the electronic ballasts wouldn't hold up to the high temperatures. That was during a conversation about how they managed to stick a 150w electronic ballast in the middle of their Aquaspacelight fixture to run the 150w 20,000K BLV DE lamp that they were installing as an option instead of the usual two 24w Osram blue PC actinics. He said the little 150w electronic ballast was adequately shielded from the heat of the two 250w lamps and their magnetic ballasts.

Then, about a year ago, they announced that they would be offering all electronic ballasts (onboard) as an option on many of their fixtures. I don't think any of those have ever made it over here yet but I really haven't checked lately. I have no idea how they managed to do it, if they did it, but I guess they figured out a way to insulate the electronic ballasts from the heat of the lamps?