Convert one MH bulb into two?

sueandherzoo

Active Member
Sorry if this is a stupid question but I'm pretty new to the world of metal halide lighting. I recently purchased a custom-built used canopy for my 92 gallon corner tank which has a 400w, SE metal halide fixture in it. I'm now in the phase of experimenting with what kelvin option I like best and have had a 20,000K in there. It's nice to look at but my corals don't seem to be doing that great. I just put a 5500K in there but it's much too yellow for my preference (even though the corals already seem to be responding better). So I'm on my way to pick up a 10,000K, but my husband asked me a question which has me wondering..... is there any type of converter or fixture that I could plug into the mogul that would then allow me to use two different bulbs in that fixture? Obviously since the ballast is for 400 watts I would have to use two-200 watt MH bulbs, but then I could really go nuts playing with kelvin combinations.
Is something like that possible or feasible? Does such conversion equipment exist?
Thanks in advance.
Sue
 

meowzer

Moderator
No clue about the conversion thing...LOL....BUT have you looked into 14K......they are not yellow, a tinit of blue...and my corals seem to grow great, (I have 250W and 3 of them)
How many bulbs does this unit take? Do you have any actinics???
 

sueandherzoo

Active Member
Hey Lady.... long time no see! (my fault, not yours)
Yes, I am probably going to order a 14,000K (there's no one locally who has one in stock) but I am intrigued by hubby's idea of having two bulbs instead of one. It's a corner tank so there's not a whole lot of room (or options) for lighting up there in the canopy.... it came with a big reflector and one mogul. If I added any strip lighting I would be blocking some of the MH rays.
Sue
 

geoj

Active Member
By no means am I an expert on MHs, but it is all in the ballast, If it is designed to run 1 at 400w or 2 at 175w then your good to go other wise your out of luck.
 

sueandherzoo

Active Member
I was at one of my local LFS's tonight and asked the question and he said the same thing.... he doesn't think ballasts are built to fire two bulbs unless that is what it was designed to originally do. Still not sure why it can't fire up two by firing the one original mogul, but I know close to nothing about this equipment so I'll trust the experts.
Sue
 

acrylic51

Active Member
No.....If there is 1 socket it will only fire 1 bulb.....If your looking for better coloration, your on the right path of looking at 14k bulbs...You might want to personally see different bulbs over a tank if possible, or even online looking at tanks you can get a general idea on the look of a bulb, but the 14k will definitely be "blue" compared to what you have...Some people use straight up 20k bulbs depending what their preference is.......
Maybe Spanko or NikeSB will chime in coloration!!!!!
 

acrylic51

Active Member
Are you possibly referring to a twin arc bulb?? SCSInet or another person awhile ago was talking about that, and they might better be able to give you some info on that bulb.
 

2quills

Well-Known Member
Quote:
Originally Posted by acrylic51 http:///forum/thread/381834/convert-one-mh-bulb-into-two#post_3328813
Are you possibly referring to a twin arc bulb?? SCSInet or another person awhile ago was talking about that, and they might better be able to give you some info on that bulb.
Those are pretty neat and would/could be a good alternative. You won't be able to run two bulbs off of your ballast they are not designed to perform that way unless it states otherwise. But basically it would have to be two ballasts in one. The twin arc (mogul base) bulbs have 2 bulbs within 1 bulb basically...10,000k & 20,000k. Although they don't run at the same time. What they do is they alternate when the bulb is turned on or off. For instance if you turn the bulb on it comes on in 10k, and then if you turn it off and then back on it comes on in 20k. Essentially what you could do is time your bulbs to come on in 10k while you're at work and then come on in 20k when you come home so that you could have the better growth period when you're gone but nicer color when you're home. I'm not sure how well they look either. I just thought they were a nifty idea.
 

sueandherzoo

Active Member
Thanks for the info.... I'm off to go read up on twin arcs - sounds like a really cool concept but, like any cool concept, it's probably got its share of downsides, too.
I have had a 20,000K on my tank since I bought the canopy with MH and it brings out great colors but it was really almost TOO blue. I picked up a 10,000K last night and it's crisp, clean, and white but now I'm missing the blue a little. Sounds like a 14,000K is probably what will make me happy. But wow.... being able to have it at a low kelvin while I'm at work and a higher Kelvin when I'm home is really an appealing idea.
From looking at different bulbs at the LFS last night I learned that not all 20,000K's are the same. His were not nearly as blue as mine was, so I guess another part of the challenge is finding the right manufacturer, the right K rating, and the right ballast to get the desired result. Yet another "trial and error" facet of this hobby. :)
Sue
 

geoj

Active Member
Quote:
Originally Posted by SueAndHerZoo http:///forum/thread/381834/convert-one-mh-bulb-into-two#post_3328864
Thanks for the info.... I'm off to go read up on twin arcs - sounds like a really cool concept but, like any cool concept, it's probably got its share of downsides, too.
I have had a 20,000K on my tank since I bought the canopy with MH and it brings out great colors but it was really almost TOO blue. I picked up a 10,000K last night and it's crisp, clean, and white but now I'm missing the blue a little. Sounds like a 14,000K is probably what will make me happy. But wow.... being able to have it at a low kelvin while I'm at work and a higher Kelvin when I'm home is really an appealing idea.
From looking at different bulbs at the LFS last night I learned that not all 20,000K's are the same. His were not nearly as blue as mine was, so I guess another part of the challenge is finding the right manufacturer, the right K rating, and the right ballast to get the desired result. Yet another "trial and error" facet of this hobby. :)
Sue
There are some www's that have some data on bulb-ballast performance it is incomplete but you can get some idea as to what bulb to use with your ballast. Do a search "Spectral analysis of 400w metal halide lamps" and compare your ballast.
 

sueandherzoo

Active Member
oh wow..... just read the whole thread on the twin arcs (thank you for the link) and what a neat concept - I want one! Of course I need to go read somemore and see if there are lots of negative reviews on them but it's fascinating to learn about this stuff while I investigate. I'll definitely also look up the different spectrums/different ballasts. Thanks for the leads!
Sue
 

acrylic51

Active Member
From what I remember SCSInet talked about wet neat, but they have issue, and don't think they took off like they thought.
 
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