2x175 watt MH or 1x400 watt

[Guy]

I am looking for some suggestions.

 

I have a 29 gallon which is now running a 175 MH pendant. I have a mix of some softies and a few acropora frags.

 

The pendant lights the center of the tank well but the sides are a bit dark. I was considering adding a second 175 (which I already own) and hanging them side by side, which would solve the shading issue etc.

 

Here is my question. Is it more economical to run a single 400 watt unit, or will the 2 x175 cost about the same to run? I realize if watts are the only factor they will be about the same, but it has to cost more to run 2 ballasts versus just one. Or does it?

 

The obvious disadvantage is that I will need to purchase a 400 watt set up and it will still light the center brighter than the sides.

 

Any suggestions are appreciated.

 

Guy

[Physh1]

I don't see it being cost effective to buy a 400 watter. I'd personally run 2 - 175's myself. The light distribution will be even and you already have it.

 

On the kinda bonus side if you ever go to a bigger tank 1 - 400 will probably not be at all adequate but 2 - 175's will be better for tank upgrades.

 

Cameron

[anthony812]

just one 175W is enought for a 29 gallon tank..in those areas that doesn't get mch light..you can put your softies there, or light sensitive corals in that area..Monti Cap / digitatas normally don't require lots of light and so you can put those ont he shaded areas also...but if you really want to do it right..I would just use a 400W like i have on my setup..my tank is 30"x24"x18" and i use a single 400W the whole tank is well lit...

[Pikelet]

You need to get the efficiency specs on the ballasts to work that out accurately if you are considering power consumption alone. I suspect that there won't be much in it(10-15%) because the ballast for the Radium will probably be more efficient than those for your pendants.

 

Just a couple of points to make. Darker parts of the tank are not necessarily a negative. Two pendants over a small tank look naff IMO and will require a rewire in the ceiling. Radium 400 might need some supplementation with 10K on certain ballasts depending on your lighting tastes.