Enough Lighting - The Planted Tank Forum
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post #1 of 4 (permalink) Old 05-20-2005, 09:23 PM Thread Starter
Algae Grower
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Enough Lighting

I have a 2.5g hex tank that I trying to get a high amount of lighting in. The dimensions on the tank are 9" high by 4" sides. If I have done things right, the surface area should be 31.14.

As far as the lighting is concerned, would a 15 watt cf spiral light be sufficient? I have looked at rexgriggs.com and this is what I'm comming up with.

31.14 - Surface Area
30 - LSI High Light
800 - Lux Rating
31.14 x 30 / 800 = 1.16

Where am I going wrong or do I need to go with a higher wattage bulb? Thanks for your help.
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post #2 of 4 (permalink) Old 06-05-2005, 05:58 PM
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your bulb is fine. it is giving off 6 watts per gallon which more than enough. if you are trying to grow live plants this will perfect. 2 or 3 watts is the minimum. it sounds like your tank is fine where it is. peace
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post #3 of 4 (permalink) Old 06-05-2005, 06:59 PM
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Spiral lights arent very effecient for getting light into the tank.
Coralife sells 20 watt compact flourescents that screw into a normal socket though. That would work alright.. and It only costs about 10 dollars from www.bigalsonline.com
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post #4 of 4 (permalink) Old 07-04-2005, 03:43 AM
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I've read Rex's article before and in theory aggreed with him. I took a look at your math and it didn't make sense to me so I went back a reread his article.
I sat here with my trusty ti-83 and followed his math out. It still made sense till I got to the last paragraph. The way he describes how to figure out the LSI seems nuts to me. If you want to find out how lumens per square inch you have you simply divide the lumens you have by the size of the surface of your tank (in square inches {l*w}). Now if your math was good comming up with the suface area of your tank then you lsi works out to 25.690 lumens per square inch. That puts you in the high end of medium light to the low end of high light.

I just went back and reread his article a 3rd time. The last paragraph is how to determine how many actual lights you would need to get to that level of lighting. So your math is correct you would need 1.16 spiral lights to reach your desired lsi. Or if you use just one you wind up with 25.69 lsi.

I hope I've helped you out and not confused the crap out of you.
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