lighting question?
 

Y do people say MH uses a lot of power?? Wouldn't 250watt MH and 250 watts of T5HO use the same?? Amount of Electricity

They are the same. Sort of like 100 pounds of lead and 100 pounds of feathers.:biggrin:

they use more power because you usually need more halides compared to less t5,s......say on a 4ft tank you would want 2 x 250w halides while you could easily get away with a 4x 54w t5s.......on a 24" tank you would only need one halide but you could still use the same 4 bulb as before.so its all compared to the size of the area you want to l;ight and how many lights you are running.

im not sure on the comparison between 250w of halide vs 250w of t5 thanks:)

heres why;

example;

a tank has a 48"x12" foot and is 18" deep would need two 250w halides which is 500w.

the same tank would need 4 48" t5 bulbs (54w a pop) - so thats 216w.

omg we posted the same THING! i swear your post wasnt there when wrote mine! LOL

Well, a bit subjective here. The tank in question doesn't "need" 500w, only if you're using 250s. You could easily light the same tank with 2 x 70w, or 2 x 150w. Now this addresses light spread and coverage. What is in the tank may have different needs. I don't use T5s, but 4 x 54w seems low if I'm running an 18" clam tank. I would think that more than 4 tubes is "needed" . I could be mistaken, as I said, I don't use them, but "need" is a subjective term.
In comparison for cost, you need to compare costs of bulbs over time, costs of power, for MH, costs of cooling any heat generated. I know my chiller currently costs almost as much as running a second set of T5s :)

I don't want to split hairs :Banane34: but arent we supposed to be comparing 250 watts to 250 watts.

Yes, I think the original question was comparing watts of equal output.

Ok I have a cube tank 24x24 by 30 high I have 2 175 watt MH mogul I can use or buy a t5 fixture. Goiing to have a mixed reef.so am I gunna consume more power with MH of t5 same wattage 350watts

On that size tank, I'd probably just use the 1 MH. It will cover a 24x24 area. At 30" deep, you'd need to keep more light demanding critters higher up.