Retrofit T5 light distribution

Papillo

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15 Jun 2008
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I am planning on retro-fitting some T5's into my hood over my 4ft x 18' x 18 ' tank with the lights about 10 cm above the water surface . My question is will I get an even spread of light if I use a twin tube unit or would I be better off getting two or three seperate lights so that I could spread them further apart?
 

GreenNeedle

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I assume you are buying tubes the width of the tank? Therefore you are asking about wether to get a light unit which will have 2 side by side (front and back) or 2 seperate ones that you can position where YOU want them.

I think you already know the answer here. Much better to put them where you want them. I divided my hood into 3 in my mind and then postioned the 2 tubes inbetween each third.

Andy
 

Papillo

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Yes, I'm talking about 54w 120cm lamps along the length of the tank. It seems to me that if I buy one of the twin light units such as D-D or Arcadia the lighting will be concentrated in a narrow strip down the middle of the tank, leaving the background and foreground plants relatively short of light. That is unless there is enough light spread to light the whole tank from front to back? Aaronnorth thinks that will be 'OK'. Is that OK fine or OK just about?
 

Papillo

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OK it seems that seperating the tubes is the way to go but if I buy two seperate units like the D-D razor it makes it more expensive. The alternative is to to buy a seperate starter unit, bulbs and reflectors which would be cheaper, but then it would be better in my setup to fix these to the underside of the hood whereas with lighting units I could rest them across the top of the tank and then slide them back and forth which would be a more flexible arrangement. Any thoughts? Also does anyone know whether the Arcadia twin T5 ballast can be run with just one bulb? I'm thinking that if I get two twin ballasts then I can run any combination of 1-4 bulbs.
 

Ed Seeley

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I've found on my 36"x18"x18" tank that the light distribution was fine with a double unit (a T8 one though) that I positioned just to the front of halfway back. My thinking was to have the most light over the front and middle sections as the back would grow taller and therefore nearer the lights. It also reduces the shadow effect when fish swim near the front of the tank.
 

Papillo

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Thamks for the input guys, trouble is I'm now back where I started :? As far as lighting is concerned A twin unit will probably be OK but seperate lights may be better. As far as cost/convenience is concerned a twin unit may be preferable. So now I'm dithering again! Any other input to help me make a decision would be welcome.
 

Ed Seeley

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3 Jul 2007
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Go with a good quality twin unit like the D-D one IMHO. Dead easy to fit, neat under the hood and I believe that unit comes with their gull-wing reflectors which are about the best you can buy. I retrofitted them to my Jewel lights and they are excellent.
 

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