I recently set up DIYMH on my 125g. Three 250w 10,000K XM bulbs on magnetic ballasts. One of the bulbs was on another tank for about a month before I put them all over the 125g. While over the other tank it began to look very yellow. It was tight in its socket. I looked up my problem in the various forums and the best that I could come up with was that some people have better output (not yellowish...I don't have any meters to really test output) when the nipple is at the 3 or 9 o'clock position. I tried this and it worked. But the bulb is no longer tight in it's socket. Is this a problem or is loosened a 1/4 turn ok? I may be able to take the socket apart, but this would only fix the orientation for this particular bulb. Today the bulb started looking yellow again while at the 9 o'clock position. I shut it off, tightened it (nipple in ~12 o'clock position) and restarted it 15 minutes later. It was still yellowish. I left it on for about 1/2 hour and then shut it down, loosened it to the 9 o'clock position and restarted it 15 minutes later. It is back to the white color. Any ideas why this is happening? Any one have similar experiences? And lastly, does anyone know of an easy way to look up metal halide in the forums using the forum search button when most people use "mh" or "MH" and the search does not work for 2 character words???
Look to be perfectly honest, word around the camp fire is that we dont even use the bulbs long enough in appliaction to warrent any change in nipple dirrection to begin with, & certainly not as long as any manufactuers are claiming. Lets take another journey of that same camp fire & say that nipple downward applications can indeed decrease light, hence the collection of non vaporising halides to which end darkens the glass nipple area, and thus compounding the already weakest link in the quarts sleve, to which end temperature absorbtion within the sleve itself can effect colour spectums enough to play havic with curved outputs.(wow, what a mouthful)
thirdly this topic is so open to debate because of the shear differences not only within the makes & models but within batches of the same products. As much as i love MH , its a subject id love to hate! Being that the variables are almost endless it very hard to put a definate answer to a question. The amount of air flow, the amount certain areas of the bulb absorb different spectrums, whether they are double ended aray, the list goes on & on & on! you kinda see where im going with this! Unless you can hold up your hand held device & quote the values that are being projected its an open-ended disscussion. & personally as every man or woman before you id suggest you continue along the path of personal choice!
Veriann....are you sure you did not have the scotch before that reply?
Doctor.....I had read those, thanks
I believe that nipple orientation is probably not the cause of the yellow color issue that I have had. I probably should have used bracket position in describing the orientation just to get away from the nipple thing. I feel that the author of the articles needs to test more bulbs perhaps. The statement "Under certain sets of circumstances it might be possible for some metal halide bulbs to appear yellow." seems a little weak to me. I would say that it "is possible". I have one. I do not think I could recreate the color shift to yellow either, although, I was able twice to get it back to white by reorienting it.
Do you have any way to check the power consumption of the ballast? What brand is it and how old is it? Magnetics usually aren't nearly as accurate as electronic ballasts, and with 3x250 a slight power fluctuation could probably impact the bulb output.
No, I do not have a way to test power consumption.
It is and Advance ballast purchased in June but not used until the end of August or the beginning of September. It was the only ballast in use when the problem first occurred. If the problem was due to the ballast would it not seem strange that changing the bulb position fixes the problem.
No, I do not have a way to test power consumption.
It is and Advance ballast purchased in June but not used until the end of August or the beginning of September. It was the only ballast in use when the problem first occurred. If the problem was due to the ballast would it not seem strange that changing the bulb position fixes the problem.
Yeah, I guess that would be strange... maybe a loose wiring issue or something could explain it though, is it a perfectly repeatable problem in those 2 bulb positions? Also, how much "yellower" are we talking?
It is hard to say that the problem is perfectly repeatable. Originally when the bulb was first put in I tightened it and did not worry about any particular position. The bulb was a nice crisp white for about a month then got yellow and dimmer. I did the searches in the forums and came to the conclusion that some people believe nipple orientation matters and some do not. I also found a few posts that said for XM bulbs having the nipple or bracket in a horizontal position gives better (brighter or whiter) output from the bulb. I had already tried taking the bulb out and re-seating it. It was still yellow. So I turned it a 1/4 turn loose to put the bracket in the horizontal position and restarted the lamp. Back to crisp white. I did not mess with it after that. Yesterday it turned yellow again...not really yesterday...I think it starts just a little yellow then gets worse each day. Anyway, it was already in the horizontal bracket position so I tightened back up 1/4 turn. Restarted the lamp and it was still yellow. I let it run for awhile and it never got whiter. I then shut it down loosened it 1/4 turn to the horizontal bracket position and it was back to crisp white. it definitely is not as white as the newer bulbs but I expect that. The yellow color is awful. I can try tightening the bulb up now that it is in its white phase to see if it turns yellow.
I did the searches in the forums and came to the conclusion that some people believe nipple orientation matters and some do not. I also found a few posts that said for XM bulbs having the nipple or bracket in a horizontal position gives better (brighter or whiter) output from the bulb.
I think Rob uses XM 10K 250W, maybe he can chime in on this... do ALL your bulbs do this? Does this one bulb do it in multiple fixtures?
Here are some pictures. I forgot that I had a tripod so they are not from the same position but I think you will see the difference. The first picture is turning the bulb tight in the socket which places the nipple/bracket just right of vertical. The bulb had been in the "whiter phase" prior to turning it. The second picture is after turning the bulb back to the loose horizontal nipple/bracket position. The xenia is all the same and yes there is too much of it.
I will try this bulb in one of the other ballast setups.
In the Google search box type "site:www.talkingreef.commh" and it will only search that site. There is no space on either side of the colon but there is one between the site you want to search and the term you are searching for.
I have concluded that it is not the bulb. Moving the bulbs around to different sockets yielded the same results as above for the new bulb and the old bulb was "crisper" than it had been. I guess I will check out the socket and wiring next.
The problem turned out to be a bad capacitor. I replaced the capacitor with a new one and have not had problems since. I still do not understand why changing the bulbs position had the effect that it did.
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