Lighting Question

[bizzy928]

Hello,

I just did a search and I didn't find any answers to my specific question.

10 Gallon
1 Month fishless cycle
No fish

I was thinking about gettin two CF bulbs that are rated for 60w while consuming only 14w.

If I install those that would mean my tank is getting 12 watts of light per gallon of water.

I have not decided if I am going to get plants or not yet...

However, I'm concerned about the fish. Is that going to be TOO BRIGHT for them? Or is it okay?

I am thinking about getting a Dwarf Lobster and maybe a school of barbs.

THanks!

[Heady]

Some fish are more sensitive to bright light than others. Look up the species profile; sometimes it will say something like "appreciates diffuse light" or floating plants or something.

[slipknottin]

No lighting system puts out more watts than it uses.

I believe the "60 watt" figure your using is the marketing comparing the bulb to a standard incandescent bulb. The CF bulb is most likely just a 14 watt bulb.

Two of these would give you 2.8 watts per gallon.

[bizzy928]

Originally posted by slipknottin
No lighting system puts out more watts than it uses.


Could you please explain scientifically?
From my point of view, the variable we are looking at is Light Output.

Lets say we have:
Compact Flourescent
Input = 14w
Output = 60w Equivalent

Incadescent
Input = 60w
Output = 60w

Now what is the difference between the light outputs? ~0watts of light output.

So if we were measuring output of 1 CF and 1 Incadescent bulb in a 10 gallon tank using the above specs for the bulbs, the output would be 60w/10g = 6watts of light output per gallon for each type of light.

That is why they invented flourescent bulbs in the first place. You have less energy consumption and more light output compared to leading incadescent bulbs.

PLEASE correct me if I am wrong.

[andruboz]

i thought light intensity was measured in lumens.

http://www.energybooks.com/pdf/D1150.pdf

my other assumption is the wattage on incandescants is mostly heat. that you dont need.

i just bought some 19w 6500k spiral flourescents that put out 1100 lumens. ( the equivalent of a 75 watt bulb according to the packaging. )

i plan on using 7 of them on my 125g with one grow light for the planted corner.

[ChilDawg]

lux/lumens or foot-candles/candlepowers/candelas

The candela is gradually being replaced in the states.

1 foot-candle is approximately 10.74 lux.

sunlight on an average day ranges from 32,000 to 100,000 lux
TV studios are lit at about 1,000 lux
a bright office has about 400 lux of illumination
moonlight represents about 1 lux
starlight measures a mere 0.00005 lux

[bizzy928]

Since not everybody is aware of the amount of lumens a 60w incadescent light has, and the amount of lumens a 14w CF has, I used "watts" as the measure of light because everybody probably has a vague idea of how bright a 60w incadescnet is...

So back to my original question :)

Do you think 12 watts per gallon of light is too much?

Thank you.

[slipknottin]

:rolleyes: I already told you, its not putting out more light than your using. Its mechanically impossible for it to do that. Your making a comparison to a very inefficient lighting source. Id say 99.9% of the people on this website are using fluorescent lighting. It is standard for us to use the actual wattage rating of the bulbs, not a comparison to incandescent lighting.

You only have 2.8 watts per gallon. And for most fish, it shouldnt be a problem. Its still only 28 watts of light. watts per gallon is a horrible rule of thumb.

[Molino]

I've got two 13 watt CF lights on my 10 gallon planted tank. They seem to be working fine so far (~1 month). You should be alright with two 14 watt CFs.

edit: There are some threads regarding CFs in the planted tank section that you might find interesting. I think there's a way you can search for certain topics.

[bizzy928]

Originally posted by slipknottin
:rolleyes: I already told you, its not putting out more light than your using. Its mechanically impossible for it to do that. Your making a comparison to a very inefficient lighting source. Id say 99.9% of the people on this website are using fluorescent lighting. It is standard for us to use the actual wattage rating of the bulbs, not a comparison to incandescent lighting.

You only have 2.8 watts per gallon. And for most fish, it shouldnt be a problem. Its still only 28 watts of light. watts per gallon is a horrible rule of thumb.

Can you point me to a website of reference please?

[slipknottin]

reference to what?

When we use watts/gallon we are referring to fluorescent type lighting. Otherwise my 90 gallon tank would have around 50 watts/gallon of lighting, and my 10 gallon tank has something like 90 watts/gallon.

Watts/gallon is a horrible rule of thumb anyways, 28 watts of CF lighting is only going to be around 2100 lumens. Not that bright at all.


from thekrib.com
conventional incandescent: 500PAR64, 6500 (initial) lumens, 500 watts,
13 lumens/watt
halogen: 50PAR30 (GE Halogen IR), 1000 lumens, 50 watts,
20 lumens/watt
fluorescent T12, GE Chroma 50, 1870 lumens, 40 watts,
46.75 lumens/watt (on a ballast that only draws 40 watts, heigh ho)
fluorescent T12, GE rare earth, 2960 lumens, 40 watts,
74 lumens/watt (but this depends on the ballast)
fluorescent T8, GE rare earth, electronic ballast (!), 2650 lumens, 27 watts,
98 lumens/watt
fluorescent compact F40/30BX/IS, electronic ballast, 2840 lumens, 30 watts,
95 lumens/watt

[bizzy928]

Okay, lets just scrap the whole watts per gallon thing.

10 Gallon Tank
2x14w CF that output 800 Lumens Each (1600 Total)
The colour temp of each bulb is 2700k

1) Will that be too bright for my fish in terms of lumens?
2) Will that be sufficient lighting/nutrients for one aquatic plant with no CO2?

My concern was that with the existing incadescent bulbs rated at 25w and lets say 600*2 lumens, if I exchanged the 25w with a 14w CF that outputs 800*2 lumens, that extra 400 lumens is going to be to bright for my fish and their eyes.

[ChilDawg]

The answer: it depends. Nothing is too bright for fish if they are provided with sufficient floating greenery to diffuse and even block out light altogether.

[bizzy928]

Originally posted by ChilDawg
The answer: it depends. Nothing is too bright for fish if they are provided with sufficient floating greenery to diffuse and even block out light altogether.

Could you name some examples of "floating greenery?"
Meaning it does not have to be planted?

Are these plants hardy? And would 2*2700k CF suffice for their survival without CO2?

[ChilDawg]

I'm thinking about duckweed in particular, but I don't have a good grasp on what it would need for lighting/CO2 requirements. Hopefully someone else could answer that!

[slipknottin]

If your refering to the floating greener when you ask of C02 then its a mute issue. Floating plants can take C02 direct from the air.

As for the bulbs, if you can, I suggest you find bulbs with a higher K value. A bulb of 2700K will be predominatly in the red and yellow spectrum. Plants benefit from a spike in both the yellow and blue spectrum, which is why bulbs of around 5500K are most common and most recommended.