MH/Ballast Question, also opinions

[Doherty]

Hi everyone have a few questions and looking for opinions on MHs. I will be starting back up again after a few years of being tankless. I will be setting up a 40 breeder that was given to me by S_Kelly (thanks again Shane). I had wanted to use my 150 w MH pendant fixture, however I'm not sure if I will get the spread needed to cover a 36" long tank. I plan on keeping a few Nems, and will mainly be softy/LPS dominant, I don't intend on keeping any SPS.

Few Questions/Opinions

1. Do you think I will have enough spread with my 150w pendant fixture?
2. If not, would I be able to use my existing 175w electronic ballast to power 2, 70w pendants for better coverage. Knowing my lighting requirements do not need to be extremely high.
3. Opinions if 2, 70w MH fixtures to cover a 40 breeder would be enough for Nems/softy/LPS mixed reef. Or if I should just add another 150w fixture.

Thanks Guys

 

[Trevor]

I think the single 150 should be enough, try it out, if you think you need more add a second, I have a 150 over my 20L and think its plenty, I would use it over a 40 also

 

[JohnK]

I've run a single 150W over a 40 as a temp holding tank for frags. It's deccent light in the center but definately drops off at the ends quite a bit. You certainly could cluster the light demanding livestock around the center, but as a display it would look a bit odd IMO with the drop off.

You can't run 2x70W off of a 150W ballast. You would need 2x 150w ballasts to do that.

 

[Doherty]

Thanks for the input guys.

I don't know much about MH Ballasts, just curious why you cannot run 2, 70w MH lamps of of a single 175w ballast if wired together, I've never heard this asked before on the boards. Not questioning the answer John, just curious for my own knowledge.

 

[Trevor]

Thanks for the input guys.

I don't know much about MH Ballasts, just curious why you cannot run 2, 70w MH lamps of of a single 175w ballast if wired together, I've never heard this asked before on the boards. Not questioning the answer John, just curious for my own knowledge.

I also would be curious for this answer

 

[JohnK]

Each ballast is spec'ed to go with a specific type of bulb. You could try it with an electronic ballast, but I wouldn't suggest it. Parallel or in series?

 

[JohnK]

Not very controlled or definitive but
http://www.reefsanctuary.com/forums/diy/19360-2-metal-halide-bulbs-one-ballast.html

 

[Doherty]

It would prob be wired parallel if it were something I would had considered doing.

 

[Doherty]

Not very controlled or definitive but
http://www.reefsanctuary.com/forums/diy/19360-2-metal-halide-bulbs-one-ballast.html

Interesting thread ..... Thanks for that John. I honestly never thought about this before today.

 

[JohnK]

I've been googling for the past few minutes trying to find you a clear explanation and I'm not finding it. Lots of what you got from me, "you just can't do it {But I can't actually explain why}". I can't explain why

 

[JohnK]

Here's what we need. I don't know if it specifically says you can't run 2 lamps on one ballast, but this gives a sense of how complex the whole MH ballast x blub thing is.
http://reefkeeping.com/issues/2007-03/sj/index.php

 

[Doherty]

Thanks for all that research John..... I just looked though that info..... Pretty complex stuff.

 

[dz6t]

Metal halide ballast is to limit the current to prevent it going higher when bulb is burning because the resistance goes down when the bulb is burning and cause the current goes up. I never see people use one ballast on two bulbs.
there are dual-lamp bulbs available but only one lamp is burning each time.

 

[dz6t]

In case you are looking at dual ballast, it actually has TWO ballast in one enclosure.