should i get MH 250W or 400W

Hi,
i'm investing in halide lighting. I'm getting a pair of ballast for 250W or 400W for the same price, as well as the bulbs for the same price.
I'll be supplementing the halides with 165W of PC. This is all going into a 55gallon tank.
So which ballast should i get? I know its probably better to have more light, but at the same time my electric bill is gonna be though the roof...
In my tank right now there are mainly soft coral, but i plan on adding some SPS.
the last question is if i purchase the 400W ballast can i put 250W bulbs in it. Kinda like how our lamps at home say put in a 100w bulb and we put in 60W.

thanks for any help.

 

Here is a good article with a cross reference of bulbs and ballasts link.

http://www.aquarium-lighting-guide.com/metal-halide

I am not 100% sure, but I don't think you can drive a lesser watt bulb off of a higher watt rated ballast...

You said you are getting a pair? So you would have 2 x 250 W? That , IMHO, would be more that enough even for clams and sps corals.

I have a 175 on my 58 gallon with 2 x 96W PC Plan on upgrading to a 250 eventually.

I have a friend who upgraded to 400's and ended up taking them out and going back to the 250's due to serious heat issue.

 

yeah its a pair of either 250W or 400W so that would be 500 or 800W total. Is the 175W that you have times two, or just one? why are you upgrading?

 

I think 400s would be over kill. how deep is the tank?

It is not possible to drive different wattage bulbs on a ballast, you need the righ bulb for the right Ballast.
the type of ballast is also very important. There are several types Pulse, Probe, and HQI

J

 

That article has a link to matching bulbs and ballasts.

I have only one 175 bulb. It is an old setup, and the ballast makes all kinds of banging noises on startup..so I figure, If I am going to upgrade, I may as well do a 250. The sides of my tank are pretty shaded so trying to brighten it up a bit. Right now I have mostly lps (my fave!) I think I will go to a 6500K bulb for growth and keep the actinics for color ;D I don't want more than one bulb tho. I have a beautiful clam as well, has gotten big over the last 6 months too!

 

yeah the link that birdlady has shows that most bulbs are a probe start, and there are a few pulse starts, but those are mainly european ballast i guess.
The tank is a regular 55 gallon, i guess that makes it about 20 in.

 

i have seen a 55 tank that had 2 250w 65k metal halides and a 96w actinic pc and it was the best tank i have ever seen. i agree that 400's would probably be overkill and unless you have a really tall hood you will probably have massive heat problems.

 

heyh birdlady maybe you should go for 2 175w mhs that way there would be no chance of shaded corners

 

I like the shaded corners ;D Good for shrooms and I like LPS some cannot tolerate as much light. So I have options!

I believe if you get an electronic ballast, you can drive either type of bulb...could someone confirm or deny this for me?? ;D