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Discussion Starter · #1 ·
Hey p-furyans,
I have been focusing mostly on salt water lately and was curious with lighting. I use MH lighting on my saltwater tank because it closely resembles the sun for corals that need this for photosynthetic processes. I love the shimmer affect and how natural it makes things look.

I was wondering why no one does this with their piranha tanks? The bulb is UV shielded and definately not nearly as powerful as the real sun so I don't think it could damage a piranha's eyes. Do you think a piranha could adjust to this type of lighting, would it hurt the piranha, etc.?

Thanks for the responses
 

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these cold eyes lock much wonder...
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wouldnt it get a little hot?
 

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well heat ofcourse can be an issue with halides. but aside from that well the question is of course how much wattage is the bulb? If its one of the lower wattage ones like a 75W or maybe even a 150. It might be ok so long as its raised above the tank some. But it still seems like it would put off quite a bit more light then P's would be comfortable with. But given some cover it might be ok.
 

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Discussion Starter · #4 ·
as with most MH lighting it would sit at least 8" above the water's surface. I was thinking of using a pendant with a 150w DE bulb, I don't suspect there would be much heating of the tank over an 8 hr period (that's how long the tank light would be on). This is not a serious plan right now, I am just thinking out loud about this and curious about what others think.
 

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How big of a tank are we talking about? planning on having plants in there? with that kind of wattage not having plants could raise some serious algae issues.
 

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Discussion Starter · #6 ·
a 40g tank. some one told me that the color spectrums of the bulbs are too different for sw color temps and fw color temps. in other words, a 10k or 14k bulb would not grow much algae in a freshwater tank and would not work for growing freshwater plants because of the color spectrum. They said you would need something along the lines of a 4500k or 6500k for freshwater growth. what do you think?
 

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Metal halide bulbs are OK in freshwater systems and also for Piranhas.
But you will need them only for plants, not for the fishes.

It is true that halides produce heat (like mercury vapour bulbs) and there must always be a distance of 1 foot between bulb and top glass or water surface.

For marine tanks one needs to have those 14.000 - 20.000 K bulbs because the blue light (that penetrates water best) is important for zooxantheallae of living corals.
For freshwater system bulbs like 5000K - 10.000 K work best.

Harry
 

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Discussion Starter · #8 ·
thanks for all the responses guys.

Harry,
thanks for the info.

If I ever decide to put one of my halides on a freshwater tank i'll make sure to post it here for you all to see.
 

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a 40g tank. some one told me that the color spectrums of the bulbs are too different for sw color temps and fw color temps. in other words, a 10k or 14k bulb would not grow much algae in a freshwater tank and would not work for growing freshwater plants because of the color spectrum. They said you would need something along the lines of a 4500k or 6500k for freshwater growth. what do you think?
srry for the late reply. Like Harry said. So long as your halides are in teh lower range (for halides) and are 10,000K they are useable for plants. 10,000K is the upper range for FW. 4500K is too low IMO for plants and would be suitable for a fish only type tank.
I think there are some lower K halides to be found. you would just be hard pressed to track them down.
 
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^ I dont think he wants plants. Atleast I am getting the impression our friend Genin here is actually hoping that using a higher spectrum bulb will keep him from being able to grow anything in the tank.

Or maybe Im wrong?

Anyways, Ive only seen Halides go as low as 10 000k with people using FO or CF to supplement the lower spectrums.
 

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Metal halides would be great if you want a lush planted tank. Otherwise, I think it would be too expensive and entirely unnecessary for piranhas. As for the fish, they may be a little uncomfortable. Standard flourescents will do just fine to light up the tank. Most importantly it just sounds too expensive.
 

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^ I dont think he wants plants. Atleast I am getting the impression our friend Genin here is actually hoping that using a higher spectrum bulb will keep him from being able to grow anything in the tank.

Or maybe Im wrong?

Anyways, Ive only seen Halides go as low as 10 000k with people using FO or CF to supplement the lower spectrums.
Maybe not. I dunno. I don't know that any spectrum Keeps algae from being able to grow. Its all about balancing what is actually in the tank with the amount of light above it.
I think the best way to keep alage from growing would be simply to keep a nutriant free tank with low light.

tossing a halide above a non planted, non reef tank gives way too much light for alage to work with.
I mean were talking putting 2-5 WPG over the tank. thats prime Algae growing conditions unless there are plants and CO2 going in there.
 
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