[Wet Thumb Forum]-Metal-Halide light for 1000 liters

[Ofri]

Hi,
I want to light my 1000(~) liter (270 Gallon) with Metal-Halide light (maybe 3x400W + 1x250W).
The hight is 25 in.
The surface is 70x35 in.

What is the color temp (K) I should use?
Any other parameters I should consider?

Thanks,
Ofri

[Ofri]

Hi,
I want to light my 1000(~) liter (270 Gallon) with Metal-Halide light (maybe 3x400W + 1x250W).
The hight is 25 in.
The surface is 70x35 in.

What is the color temp (K) I should use?
Any other parameters I should consider?

Thanks,
Ofri

[Dojo]

Just curious, why the lone 250w?

[Rex Grigg]

Why all the light? 3x250 watts would grow almost anything one wanted to grow. 3x400 watts is going to be a true monster.

Remember that the WPG rule breaks down pretty fast on a tank this size.

[Ofri]

Sorry, I meant 2*400 + 1*250 but it will probebly be 3*400.

What about the color?

[Rex Grigg]

And again I will ask why you want all that light? 1200 watts over a 270 gallon tank is way too much light. You really need to think about this some more. 4.44 watts per gallon on a tank this size is akin to having around 8-10 watts per gallon on a smaller tank. At the very most 3 250 watt fixtures would be all you need and I'm betting that 2 175 watt fixtures are really all you need.

As for color anything that pleases you in the 5000k-6700k range will work fine.

[Ofri]

Thank you.
I'll probebly use 3x250 6200K.
Is it so not ok to use 3x400?
What happens if you use to much light?
(it costs about the same)

The reason I wanted to use more light is that I was told MH looses 40% of it's power after 6 months.

What do think?

[gpodio]

Like Rex said, in such a large tank the WPG rule doesn't apply too good, 2WPG for such a tank should be good to grow anything. Considering the length of your tank and I believe it has 2 braces, using 3 bulbs would probably provide the best light spread. So 3x175W would be my choice. If using pendants then you could go with 3x250W and simply raise the fixtures if you find the light intensity too strong. I certainly would not be considering 400W bulbs though. I also think that 40% loss is a little exagerated, changing your bulbs every 12-19 months is sufficient IMO. Using more light would most likely just cause you algae issues, plants can be sped up with lots of light and CO2 but not indefinetly, there's a point where more light does nothing good to the plants, you'll just be adding heat and problems to your setup.

Good luck
Giancarlo Podio

[Ofri]

Thank you Giancarlo for your helpful answer.

I forget to mention my aquarium has a 12mm glass roof.
Is this a problem?
Should I use more light?

[gpodio]

I think the glass lids will be fine, just keep them clean. If you are really unsure, use pendants, that way you can lower or raise them to get more or less light as needed.

Hope that helps
Giancarlo Podio