# Aquarium Lighting



## roacan (Dec 25, 2010)

Hello,

I have read that you need 1, 2 or 3 watts per gallon for a planted tank.

Using FishTank Online Aquarium Calculator it says that I have a 34US gal and using 2" of small gravel have a water volume of about 32US gal. Less all the decor, I am guessing about 30US gal of water left.

I have a 15 watt fluorescent light so that means about 0.5watts per gal.
I replaced the original light with a power-glo.

Will this be OK? If it means that the plants would just grow slowly, I am fine with that. As long as they don't wilt and die.

Also, I am planning on moving the tank in the living room and it might get some sun for about an hour or two. This would help right?

I have two bunches of wisteria, a small anubis nana, two amazon sword, a red ludwigia, two bunches of cabomba, a telanthera, and a marimo moss ball.
I am planning on adding anacharis and Philippine Java Fern.


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## beaslbob (May 29, 2009)

It would be best to get the wattage up to 1/gal or even 2/gal. 

Too bad you don't have one of the older incandescent hoods. Two spiral bulbs of 6500k 15w each would be excellent.

Of course if the tank is near a window and gets sunlight, that will help also.

my .02



Gee who would've tunk of using sunlight?


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## Gizmo (Dec 6, 2010)

As long as your plants aren't crowding each other, they should be fine. Watch very carefully for light starvation, and keep your light on for longer. If you can, however, try and upgrade to a Power Compact or a T5HO. You can even do better if you go to a hardware store and buy a shop fluorescent fixture.


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## jrman83 (Jul 9, 2010)

Just hope the sunlight doesn't cause algae problems. When you take the time your light will be on and then add in the sunlight, it just sounds like algae will take hold. You'll need to watch it.


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## mfgann (Oct 21, 2010)

The old rule of thumb was 2 watts per gallon. This was with a T12 florescent light. Unfortunately this rule doesn't really accomodate new higher effeciency bulbs like the T8 or T5s, plus there is no real factoring in reflectors. The only way to really measure all this is with a PAR meter, which is a $300-400 gadget. Not many people have that at their disposal. The best guesstimates are about 2W/gallon T12, 1.75W/gallon T8, and 1.5W/gallon for T5s for low-medium light. Spiral pigtails lose a lot of light due to "restrike" which is basically the light hitting the bulb rather than going on into the water. For those I'd aim for 2W/gallon or more.. maybe even 3W/gallon (though I haven't replaced my bulbs yet to try that).

For good reads based on real measurements try these couple of posts at plantedtank.net:
PAR vs Distance, T5, T12, PC
PAR Data-Spiral Power Saver Bulbs, lighting question

The spiral bulb discussion gets real good somewhere in the middle of the comments, so dig a bit on it.
Good luck

edit: Got the URL wrong. Fixed it. Thanks jrman.


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## jrman83 (Jul 9, 2010)

Those threads are a good read, but can hurt your head a little. The right URL is plantedtank.net.


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## mfgann (Oct 21, 2010)

jrman83 said:


> Those threads are a good read, but can hurt your head a little. The right URL is plantedtank.net.


Yeah, definitely a lot to take in. I think the biggest thing is you find out its way more complicated that 2W/gallon. I think that scaling down for T8 and especially T5 is pretty significant though. I've been running a solid 2W/gallon on the 10G with spiral pigtails, 4W/gallon on the 2.5G I think, but when I switched out the 20W T12 for 42W of T5 (Normal Output) on my 30G (making it 1.4W/G) I started having lots of algae pop up and had to cut back on lighting time. None of it is CO2 or fertilized regularly. Not as many plants in the 30G though, but that is slowly changing.


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## slurik (Dec 19, 2010)

Your plants will enjoy the sunlight quite a bit, however i would pay close attention to temperature swings in the tank. Sunlight is a powerful energy source and can dramatically increase your temperature in a very short time. Other than that, if its under control, no light you could buy on earth will ever compare to the power of our sun. If you want a more reasonable setup 1x T5HO 34" bulb will dump 39W into your tank, spanking you just over 1 W/USGal. These fixtures are rather inexpensive these days, however the best idea would be as noted to get some good mixed bulbs in your fluorescent hood if you have one, you should be able to get plenty of light with those.


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