Trying to figure out my lighting

[Smitty]

Ok, I honestly have been trying to figure this out on my own without having to make a post, but I'm way to confused by now and really need help.

Right now I have 3 lights and would really like to cut that down to two for convenience (I have to remove one strip light from the top every time I need to access the tank for feeding/cleaning/you name it).

I have one fixture (a double) that says 120 volt, 67 watt, 60 Hz. The other 120 volt, 40 watt, 60 Hz.

In the double I have two T8 bulbs, both 40 watt, one 6,700k the other 18,000k. I bought these at the aquarium store.

While posting I was told I may need more, so I got a single bulb from Lowes that is a T12, 40 watt, 6,500k (this in the single).

From the Excel sheet I got from here (if I'm using it correctly), it says "Eq T12 wpg = 2.977; Lumens = 9644; Lumens/sq in = 15.455.

Is there a way to remove one of the bulbs and still have enough lighting? I don't want to go into CO2.

Help?

 

[Purrbox]

What size aquarium are these lights on?

 

[brutus]

120 watt over what size tank?

 

[Smitty]

It is a 55 gallon... Did I forget to mention that?? Figures... 48" long, 13" deep, 18" tall.

I've been given so much conflicting information I have no idea what is what now.

 

[runninwoof]

the other question is, what is the most dificult thing you are growing? without carpet or other high light plants you should be fine.

 

[Purrbox]

That would be borderline on needing CO2 with that much light. I'd give it a go as is and see whether or not it gives you problems.

 

[Smitty]

I'm not growing any kind of grass, but that is something I want to do in the future.

The question is, can I REMOVE some of the light, if so, which one can I remove? I don't WANT all that light, I would like to get rid of 1 of them and keep two.

 

[Smitty]

One more thing, it looks like the 6500k bulb from Lowes is brighter than the 6700k bulb from the pet store? It does have a larger diameter...

 

[jsoong]

I would keep both T8 & skip the T12. The T8's are more efficient & will put out more light. <This will give you around 1.75 WPG.> Try it for a while & see if you need to add back the 3rd. light.

BTW, what we see as brightness is not what the plants see .... ofter the plant bulbs will look dimmer to us, but have more usable lights for the plants.

 

[Smitty]

How will I know if there is enough light? Is there some kind of gage to tell if there is enough, or too much? Thanks for the help.

 

[jsoong]

Well, if you have a light meter, you can actually measure the amount of light hitting the bottom of your tank. There are posts on the net of people doing that with various bulbs so we can have an idea of how much light we are getting with different bulbs. <The posts are good only if you have the bulb that had been tested in a tank about the same depth as yours.>

For the rest of us, we just watch the plants. If the plants are growing & appear healthy, we say it is enough.