400 mag Vs. 250 HQI electronic????

[frazier]

I can get a great deal on a ballast that is a duel 400w mag ballast. I was looking into getting 3 250w HQI for my 180g tank. my question is will the 400wer's be enough and how much more electricity will they use then the 3 250w HQI electronic ballast? if I go with the 400w I will then add some T5's to go with them...

 

[bertoni]

With equal efficiency, 2x400 is about the same as 2x250 W in terms of electricity. Does the tank have any crossbars? That can be an issue.

 

[frazier]

no,it's an acrylic tank.. so why does everyone go with electronic ballast's instead of mag. ballast's?

 

[DrBDC]

electronics usually run spot on as far as wattage. With the tighter control of watts and output by a digital device, it will "usually" run the bulb at better output and color. But the biggest factor for many is the heat produced by mag ballasts.

 

[Lutefisk]

<a href=showthread.php?s=&postid=9246510#post9246510 target=_blank>Originally posted</a> by bertoni
With equal efficiency, 2x400 is about the same as 2x250 W in terms of electricity. Does the tank have any crossbars? That can be an issue.

When I first read this I was confused because I always give Bertoni's posts great credence. Two 400 watt metal halides draw more power than two 250 watt'ers (800 watts compared to 500). He must have typo'd on the 2 rather than 3.

Then I read the original post and saw that the question was about two 400 watt metal halides verses THREE 250 watt metal halides.

At similar efficiency those are very close in electrical costs.

His question about the crossbars hits the nail on the head. One of the key questions is about light distribution.

I don't know what size tank fraizer is trying to light.

If it is something like a 4' 120g with once cross brace then I'd go with the two 400's if I needed intense light. On the other hand it would still be an option to go with two 250's and save on power and costs. If it was a 4' without any cross brace and I wanted that much light three 250's is an option to provide better light distribution (smaller shadows by having more light sources).

If the tank was 6' and metal halide lighting you would really need to go with three lamps - two lamps won't provide very good light coverage.

If operating cost is a consideration you can also figure in bulb replacement costs (two 400 watt bulbs are likely to be less expensive than three 250 bulbs).

Paul

 

[dippin61]

HQI bulbs are not meant to be ran on electronic ballasts.. youll get better performance running them on the preferred HQI ballasts.

 

[bertoni]

Once the bulb choice is nailed down, we can discuss the ballast issue. I think electronic ballasts can be somewhat more efficient, or not, depending on the design, but they do seem to be quieter, from what I can tell. "Efficiency" is a slippery issue when making generalizations.

And, yes, oops, I meant to type 3x250. Sigh!