Metal Halide vs Fluorescent

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GuOD

Aquarium Advice Freak
Joined
Nov 6, 2006
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I just had a quick question about these lights because we don't understand the ratings.

I've heard that MH will drastically increase utility costs each month. However, we've noticed some fluorescent bulbs have the same wattage rating as Metal Halide.

For instance, how would a 160w compact fluorescent compare to a 150w metal halide on power draw? In this case, would the metal halide actually use less power and cost less than a fluorescent?

Thanks!
 
I am not an expert on MHs, actually I just bought my first set of MHs. To answer your question, the MH will draw more power than CFs. I am probably wrong on this, but it may have to do with amps and not watts....some one can probably explain correctly. I was just taking a quick shot, to see if I have at least a basic understanding....
 
roka64 said:
I am not an expert on MHs, actually I just bought my first set of MHs. To answer your question, the MH will draw more power than CFs. I am probably wrong on this, but it may have to do with amps and not watts....some one can probably explain correctly. I was just taking a quick shot, to see if I have at least a basic understanding....

Thanks. That was my assumption too.

My computer power supply is 700w, but it doesn't even draw close to that majority of the time. I was assuming the wattage rating is something like peak and then the Fluorescent has a 50% draw while MH is probably closer to 100% or something.

I could be totally off on that though :)
 
From what I am told by my electrical engineer friend, the rated wattage is what is used. Therefore the 150 watt MH bulb will use slightly less power than the 160 watt bulb. However, the MH should put out a lot more lumens as a result of it being more efficient.
 
Watts = Power, so 150 watts is less than 160 watts means the 150 uses less power.

For example, look at the self ballasted compact flourescent lamps they sell now. They have far lower wattage ratings than the old incandescent bulbs they are replacing, yet produce the same amount of light.
 
Hmm, ok, so why does your electric bill go up with MHs? I'm not trying to argue, just trying to learn, it seems there is something I am missing....(maybe part of my brain! LOL!)
 
Go up compared to what? Compact florescents, T5 HO?

From what I've seen, most MH fixtures come with supplementary actinic lights. This causes the total wattage of the fixture to be quite high.

Also, from what I understand, the particular ballast being used on the fixture has an impact on the efficiency of the lights. So an inefficient ballast might waste more electricity. I'm just speculating though.
 
Ah, ok, that makes more sense. I was saying some folks don't use the MHs due to the increase in the bill, from VHOs or PCs, but since the MHs coupled with the other lights, the bill would go up due to the combined wattage. THANKS!
 
My friend works for the power company and I asked him the same question. A watt is a watt, no matter what. The power company bills you in watts per hour.

The largest PC bulb (in an aquarium fixture) that I have seen is a 130w.

Lets say you had a fixture that had 4 130w 36" lamps, thats 520w. Now consider that in the same space, you can have 4x250MH bulbs, or even 4x400MH bulbs. Thats a lot more power, hence a bigger cost.

Also, if you have noticed, most of the higher watt PC's are longer. I have been looking for a 24" PC bulb that is more than 65W. The increase in watts produced by the PC is, I think, a function of how long the buld is. That is to say, a 130w 48" bulb isn't really brighter that a 65w 24" bulb, it just covers a larger area. Whereas, you can get MH bulbs in 150; 175; 250; 400w for the most part, are all the same size.

My point being, the cost to run MH's increase beacuse you can increase the amount of light power for any given space.

hope this make sence.
 
john0087 said:
My friend works for the power company and I asked him the same question. A watt is a watt, no matter what. The power company bills you in watts per hour.

The largest PC bulb (in an aquarium fixture) that I have seen is a 130w.

Lets say you had a fixture that had 4 130w 36" lamps, thats 520w. Now consider that in the same space, you can have 4x250MH bulbs, or even 4x400MH bulbs. Thats a lot more power, hence a bigger cost.

Also, if you have noticed, most of the higher watt PC's are longer. I have been looking for a 24" PC bulb that is more than 65W. The increase in watts produced by the PC is, I think, a function of how long the buld is. That is to say, a 130w 48" bulb isn't really brighter that a 65w 24" bulb, it just covers a larger area. Whereas, you can get MH bulbs in 150; 175; 250; 400w for the most part, are all the same size.

My point being, the cost to run MH's increase beacuse you can increase the amount of light power for any given space.

hope this make sence.

Thanks very much. It makes perfect sense.

So my 2x130W 48" fixture will draw a lot of power @ 260w?
 
So my 2x130W 48" fixture will draw a lot of power @ 260w?

If you really want to get technical....watts = Volts*AMPS. Your 260w fixture will "draw" about 2.36amps. (260/110v) Thats how much electricity you will be using. It will be about the same for a 250w MH fixture.

Think of watts really as an output or product of consuming electricity. Its kinda like a car engine, we measure it in horsepower (output), but when we talk about how much energy it uses, we talk Miles per gallon. Make sence?

The power company using watts per hour average for your billing, but its really the amps that matter. Check out your circuit breaker in you house, it will be rated in amps not watts.

Consider this....your typical hair blowdryer uses 1300watts. Thats close to 12amps. (FYI...it takes less than 1amp to kill someone)

I do not think that you will really see a difference in your electricy bill if you run a 260w fixture 10hrs a day.

HTH

Good Luck

John
 
john0087 said:
So my 2x130W 48" fixture will draw a lot of power @ 260w?

If you really want to get technical....watts = Volts*AMPS. Your 260w fixture will "draw" about 2.36amps. (260/110v) Thats how much electricity you will be using. It will be about the same for a 250w MH fixture.

Think of watts really as an output or product of consuming electricity. Its kinda like a car engine, we measure it in horsepower (output), but when we talk about how much energy it uses, we talk Miles per gallon. Make sence?

The power company using watts per hour average for your billing, but its really the amps that matter. Check out your circuit breaker in you house, it will be rated in amps not watts.

Consider this....your typical hair blowdryer uses 1300watts. Thats close to 12amps. (FYI...it takes less than 1amp to kill someone)

I do not think that you will really see a difference in your electricy bill if you run a 260w fixture 10hrs a day.

HTH

Good Luck

John

Thanks John. I was wondering why the idea of having MH makes everyone think the bill is going up. I guess it's because most people assume MH = reef tank = 500+W going all day.

For my FOWLR tank I guess I'll be perfectly fine with the 260w fluor and will not regret skimping on the MH bulbs.
 
You wont benefit from MH anyway with a FOWLR setup , You want to start adding coral then you may want to rethink that in the future .. however there are plenty of PC success stories with low light corals so may not even need/want to go to MH. I am holding out for the LED lights that Solaris have brought to the market to come down in price .. and i think that will be my next jump.
 
MH vs CF in the aquarium world is an apple to oranges comparison. There is a big difference between a 150watt MH bulb and a CF bulb of the same rating. It is about intensity. MH light originates from a single focal point, think of it as a more concentrated light source. This gives the light much more penetration power into the tank. This is why it is preferred when keeping light-dependant corals/inverts. The down side is that a MH buib only has a throw span of about 2 sq ft. A CF bulb will give light the entire length of the tube. And yes...MH will increase your lighting bill.
 
One thing being forgotten is that while the MH bulb will be say 150W, if it is an old magnetic ballast, the inefficiency in the ballast can lead to a fairly high (I seem to recall 30-40%) increase in the power actually being drawn, so a 150W MH will put out 150W of light energy, but will actually pull close to 200W from the wall.

Electronic ballasts (as found on T5 and newer MH) are more efficient and have a lower overhead on the amount of power pulled from the supply.

The type of bulb will not increase your electricity bill per se. If you have 150W MH and 300W of T5 then the T5 will cost more to run.

Also remember the costs of replacing the bulbs, in MH there will usually only be one or two bulbs to change as opposed to 4, 6 or more with T5 or PC.
 
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