How much does the light spread out from a T5 fixture?

[mcrist]

I am looking at the ATI Powermodule 10x39W, the dimensions are 34.5" x 21.5" x 2.3". Will this light only effectively light up an area 34.5 x 21.5 or will I have some usable light outside the light’s dimensions.

The reason I am asking is that I am considering getting two of them for my 84” x 48” x 30” (L x W x H) tank.

I do not wish to completely cover my entire aquarium with light since I only place corals on my rock and not on the bottom of my aquarium. I have two islands of rock and the approximate dimensions are 30” x 30”.

 

[Jim96SC2]

Should spread light out a little beyond the ends of the actual fixture, but it'll be most concentrated under it.

 

[mcrist]

I wouldn’t expect much additional light from the length (35.5”) but what about the width (21.5”)?

 

[jthao]

I'm using 5ft for a 6ft tank. light spread is pretty good.

 

[sharky71]

for a 24 inch wide tank how many bulbs would you recommend? Is 6 enough or do I need 8 or more?

 

[mcrist]

Thanks for the information.

 

[divewsharks]

you won't see alot of light spread of the length of the bulbs, but front/back the reflectors to spread the light; but most concentrated directly below as mentioned.

on 24" front/back, 8 bulbs should do the trick.