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No, you basically cut the tube into half. But some light will penetrate through the 2 layers of glass... probably you get a bit more than 18W per tank.
hi guys, just need to confirm this once again.
am i right to say that if i use a 2ft 36watt PL on a 2 1ft cube tank(placed side by side) i get 36watt each for the tank instead of 18watt?
thanks.
No, you basically cut the tube into half. But some light will penetrate through the 2 layers of glass... probably you get a bit more than 18W per tank.
thanks jervis for the quick reply.. guess i will check around for 2ft pl which is slightly lower than 36 watt =)
I don't think you can divide the wattage in that way. Watts is the electrical power input to the PL or FL tube, the light output by the tube is lumens.
For 1 ft cube side by side, the light intensity recieved will be the same. example 36 watt tube output 1200 lumens, the 2 cube will received 1200 lumens, slight variation due to distance from tube and angle.
but the 1200 lumens is output by the entire 2ft length of the tube. as such, since only 1ft of the tube is over the cube, it should not be said to receive the entire 1200 lumens. hence, if the 1200 lumens output by the 2ft length is consistent throughout, the cube should be receiving 600 lumens as only 1ft worth of the length is over the cube. this is assuming that no ambient light escapes into this cube, which is not a realistic assumption. however, light that escapes would not be direct light akin to a bulb directly above the tank. as such, i concur with jervis's assessment of the situation, where half the light output by the tube is considered directly in the cube and ambient light still escapes through.
36watt outputs 3350 lumen not 1200lumen. 18watt outputs 1200 lumen.
What mobile2007 said is correct both tanks will indeed have 3350 lumen.
Beauty is in the eyes of the beerholder.
so if now i only have 1 2ft tube over a 1ft cube, but i wrap 1/2 of the tube in black paper such that no light escapes, will the cube still get 3350 lumens? doesn't make sense as 3350 lumens is output over a 2ft length. as such, only 1ft length of that same tube should not be 3350 lumens should it?
yes, illumnae. If you wrapped 1/2 of the tube, you still get 3350 lumen. Light simply don't worked like electrical current or water current. That's because every inches of the tube radiated equal power of light in all direction with the same intensity, in this case 3350 lumen per metre square.
Just think of the sun as an example, you will understand. The sunlight received per metre aquare is the same, even you partitioned it with walls.
To reduce ( can't divide ) the light, one have to use a shade or raising the light source higher.
so i can use a 2 ft 15watt FL lighting over my 2x1ft cube and i can get 15watt worth of lighting to each 1ft cube?
yes, that's right.
ok thanks.. that would save me some money
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