Question about new Fluorescent Light tubes.

[kaz]

ok I have t12 48''long fixture and use to have 1 bulb 2700k aquaruium plant spectrum philips light and 1 5000k I believe full spectrum philips light.
I just bought 2 40w 48''l phillips daylight deluxe bulbs that read as follow:
LIGHT OUTPUT 2325 LUMENS
40W
LIFE 20.000HRS
COLOR RENDERING 84
COLOR TEMPERATURE 6500K

is this a better source you think of lighting than what I had for low light?
I will leave on for a few weeks and say the growth and health of plant change. what are your comments?

 

[Wizzard~Of~Ozz]

Those are the T8 bulbs that I use. I used to have 4 over my 75 and 1 T12 Daylight Deluxe.

They seemed very good for the plants.

 

[kaz]

so the new ones I got that are the 6500k daylight deluxe are very good? and better than what I used to have?

 

[Burks]

Much better.

It's a better light and more efficient. You get more light per watt with T8's.

 

[Wizzard~Of~Ozz]

But they are T12's. Still they are quite good. try replacing 1 T12 with a T8.. Takes a bit more to start, but it should be a bit brighter.. if you want to experiment.. I had a shoplight (2xT12) and I replaced 1 bulb with a T8 and it worked. if I replaced both it wouldn't fire.

 

[kaz]

interesting but the t8 is less watts isnt it?

 

[Wizzard~Of~Ozz]

Yeah, but the ballast pushes it to 40w I think.. I noticed quite a difference between the T12 and the T8 when both were on the same fixture..

 

[jsoong]

The T8's put out more light per watts, so it is brighter than the 40W T12 even though it consumes fewer watts.

If you have an electronic ballast in a T12 fixture, it will auto sense the load & fire up T8's. Some of the newer ballasts for the 36W "energy miser" T12 will prob work with the T8's as well. No harm in experimenting, as Wizzard found out, even some older 40W ballasts may work with the T8's.

 

[kaz]

General Information
Ordering Code F32T8/TL865 PLUS/ALTO
Product Number 382614
Energy Used 32 Watts
Bulb Shape T-8
Base Medium Bipin

Diameter (in) 1.000
Length (in) 48.000
Average Rated Life (hr) 30,000
Light Output 2,710 Lumens

General Information
Ordering Code F40/DX/ALTO
Product Number 273599
Energy Used 40 Watts
Bulb Shape T-12
Base Medium Bipin

Diameter (in) 1.500
Length (in) 48.000
Average Rated Life (hr) 20,000
Light Output 2,025 Lumens

ok I see the lumens are about 700 more on the t8 but the watts are less and doesnt the reading consist of Watts per gallon not Lumens Per gallons?
not sure but I thank I have magnetic not electrical ballast

 

[rkilling1]

ok I see the lumens are about 700 more on the t8 but the watts are less and doesnt the reading consist of Watts per gallon not Lumens Per gallons?

http://woo.gotdns.com/Aquarium/Lighting.htm

 

[kaz]

THANKS
has anyone took a light meter and mesure the CL of the light source ont he bottom tank? from my understanding it doesnt matter how high the lumens because in so much distance if light false off at the same rate. is this correct?

 

[jsoong]

This person has done the measurments:
http://www.aquabotanic.com/lightcompare.htm

The issue of lights is much more complicated than WPG or Lumens per sq inch. Lumens are what we see, but that is not necessarily what the plants "see". So different bulbs will have different light output that is usable for plants. Then there are reflectors, which determines how much light actually get to the water & not wasted in restrike or directed out to the room. Short of using a light meter at the bottom of your tank, how much light you are getting to your plants is mostly guess work.

From what I understand, water in your tank acts as a wave guide, so the light fall off is constant. As long as your tank depth is reasonable (less than 2'), you can assume that you will lose 50% of the light from tank top to bottom. So lumens at source will matter. 50% of 2800 (the T8.) is still higher than 50% of 2000 (the T12).

 

[Wizzard~Of~Ozz]

There are too many variables to consider.. Clarity of water, AOE (Angle Of Entry) which determines how much light makes it into the tank..

The article you linked to, while great and cryptic really offers nothing to benefit anyone.. PAR is not indicated on most bulbs.. neither is LUX (which is Lumens/Sq Foot if I'm not mistaken)..

In reality, the WPG rule is about the easiest method and works for most tanks.. Just try to compensate for the Light/Watt as best you can.. The article I wrote is based on the WPG rule, but adapts it to new more efficient bulbs that have higher outputs/watt. It also attempts to help with large/small tanks. This also doesn't apply to MH or HPS bulbs, but if you're getting into that kind of lighting, a Lux meter might be a good idea for the cost..