# lighting for plants?



## awilson0001 (Sep 2, 2010)

okay, i have been to many sites that state multiple watts per gallon for plants...

my question is that 3 watts using a regular bulbs or 3 watts using florescent bulbs?

cause you can get a lot more wattage from a regular bulb, but more light from a florescent.

my wife has angel fish and a bgk along with plants in a 55 gallon, but only has 2 standard 18 watt fixtures. the spectrum is the right one for plants i think, but if i need 3 watts per gallon, how do i accomplish that?

that's like 150 watts and that does not fit in our fixture. do they even make a 150 watt tube?


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## KiDD (Aug 20, 2010)

Yes they make Fixtures that go up to and past 150w...

There are some lowlight plants out there. You might try and look into if you don't want to pay
for some good lighting.. You need lights that have a natrual spectrum range.. IE something 
that says Same as the sun..

How long have your plants been in the tank and are they all dieing?


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## awilson0001 (Sep 2, 2010)

so i shouldnt get a light that has a spectrum thats in the red or blue?

yes there are plants in the tank, but they arent dieing. most of them are sword type.
there is also some wysteria, four leaf clover, some kind of onion plant, giant hairgrass, and maybe a few others...

so the watts per gallon they are talking about is actually florescent. are fixtures that put out that wattage pricey? and isnt that bright on the fish?


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## DJRansome (Oct 29, 2005)

Those are not low-light plants. Yes IME higher wattage fixtures and new bulbs every 6 months are pricey. Watts per gallon refers to fluorescent, but with newer bulbs lumens are more accurate. Unfortunately there is not a nice neat formula for lumens.

So...easiest thing is to get 6700K bulbs. They have the ideal "color temperature" for plants.


My 38G tank fixture uses a single twin-tube bulb that is 96 watts. 
My 125G fixtures use four T5 HO single-tube bulbs that are 39W each. Two fixtures on this tank. 
My 75G has space for four tubes at 54W each, but I only need 150 watts so I installed only 3 bulbs.


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## PsYcHoTiC_MaDmAn (Dec 26, 2005)

I'm fairly certain the rating system is the same in the states.

you want to look for lights marked 965 (that said, 985 is also very good, and seems to be better if your using plants with red leaves (from an old planted thread I saw ages ago, need to dig it up to be certain)

9 refers to that its 90CRI+ 
65 refers to the colour temperature (in this case 6500)

these lights have near enough identical spectral emission curve to proper plant bulbs.

the most important thing, get reflectors for the bulbs. and single ones rather than just lining the back with foil.


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## DJRansome (Oct 29, 2005)

Must be different unless that code is somewhere in the fine print.  The bulbs are marked (if you are lucky) with the watts and the color temp. I don't see the 6500 available as often, is it compact fluorescent only?


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## awilson0001 (Sep 2, 2010)

well, the bulbs i do have are the following

18000k, 80 lux, the spectrum is about 430 on the chart.

8000k, doesnt mention lux on this one, and is high in red and blue.

so i need more watts... how about the bulbs? do they sound okay for output?


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## DJRansome (Oct 29, 2005)

If you want 150 watts I'd buy a fixture that holds the correct number of 6700 (or 6500) bulbs with the correct total wattage. Look for good reflectors and a fan.

The one I bought for my 75G which would also be 48" like you need holds 4 54W bulbs and I just use 3 bulbs.

I found the multiple bulb fixtures are wider so I also had to buy glass covers instead of the hoods I already had.

And the fixtures tend to come with at least some of the bulbs not the 6700 I prefer. So for example the one I bought had 2 6700K and 2 actinic. I removed the 2 actinic and bought one extra 6700K.


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## Number6 (Mar 13, 2003)

*awilson0001*
an 8000K bulb is likely good for plants. The 18000K one is likely useless.


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## nodima (Oct 3, 2002)

one of the plant tank forums I frequent is really big on the lights from this place http://www.fishneedit.com/

In the lighting section, one of the members did some extensive testing, and these were the best out there, due to their reflectors. And not all that expensive either. The WPG rule has been all but made useless with the new T5 and CF lights.

If you are really bored, or want the details behind my comments here is the thread:

http://www.plantedtank.net/forums/light ... 12-pc.html

good luck


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## Number6 (Mar 13, 2003)

*nodima*
personally I think the W/G "rule" barely applied to T12 bulbs even as the number of exceptions outnumbered the times it "fit" but I double agree now when we talk about T5s. 
Glad you posted! :thumb:


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## awilson0001 (Sep 2, 2010)

im gonna read through that article... from what i am seeing then, is the watt per gallon rule is kinda an old rule of thumb and with lights now adays, it is still good advice but not as critical?

i am glad i made this topic, cause nowhere can i find good info on not just the w/g but the type of bulb and how it relates to w/g...


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## Number6 (Mar 13, 2003)

awilson0001 said:


> is the watt per gallon rule is kinda an old rule of thumb and with lights now adays, it is still good advice but not as critical?


It was a "rule of thumb" that was put together to go along with the standard practice for lighting tanks. This consisted of normal output linear fluorescent T12 tubes that span the entire length and cover as much width of the tank as possible. As soon as the tank lighting style changed, or you started to consider reflectors, distance from light to water surface, distance from light to plant, specialized spectrums, internal bulb reflectors, etc. then the rule of thumb became misleading or useless (or both).

Unfortunately, this "rule" took on a life of it's own and pretty soon you had internet bickering about 2 24" bulbs vs one 4ft bulb, shop light white metal light fuxtures vs ahsupply.com polished reflectors with no one able to comprehend that it was all apples and oranges and it was just some dumb "saying" that made anyone think that 2 24" bulbs would grow what they wanted. :lol:

I once had a great tank that was one 36W bulb over a 100g 5ft long tank. I was growing crypts, sword plants and a few stems of val under the light and I had folks telling me (on the internet) that this was impossible.  Not sure how it was impossible... I had a C.F. 36W planted tank bulb over a small "oasis" of lower light plants and they grew like the water weeds they are! 
:lol:

The number one reason that the old "rule of thumb" persists is because there is no simple rule to replace it to let you know what to go shopping for. 
I'm sorry, but lighting is not simple! If it were, there would be no massive debates online by planted tank enthusiasts and reef keepers! 

If you want "shopping rules", I can give those to you... let me know! :thumb:


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## awilson0001 (Sep 2, 2010)

oh  ... you have answered it well.

just as i thought but could not confirm, you do not really need 3 w/g in all cases. you need to know what a light puts out, and add them up as needed.

this makes so much sense that bulbs of todays age put out so much more than older ones.

i mean sometimes you need 3 w/g depending on the fixture and light, but with trial and error you can eliminate some of those watts :dancing:


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## nodima (Oct 3, 2002)

Right, and watts measure the electricity used, not necessarily the light produced. 40 watts of T12 florescent will be dimmer than 40 watts of T5 for example. One other benefit of this efficiency is the lower amount of heat produced.

Number6 - if we can't argue about 2 24's vs 1 48, what fun would it be? 

awilson - to make things even more confusing - a popular belief is that the smaller the tank, the more light (in terms of WPG) is needed. So a 10 gallon requires relatively more light than a 180 gallon. I don't pretend to "get" that one, but it seems to be pretty common.


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## awilson0001 (Sep 2, 2010)

where is the best place to find a selection of plant type bulbs?


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## AnThRaXx (Apr 21, 2008)

hey man *** been doing a lot of research online lately for a similar setup. the 8k light spectrum is good 5-6.5k is more typical for plants from what i have seen. lighting fixtures designed specifically for aquariums can become pricey. but being that my new tank has a glass lid i am going with an indoor grow light system. its probably a third the total cost of a fancy aquarium light which i find most to be built for salt water anyways. ill try and find the links to these lights i have been looking at but the lumen to watt rate is really nice considering u need 1k lumens per sq foot of space being lite


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## Number6 (Mar 13, 2003)

*AnThRaXx*
it is not true that you should have 1000 lumen per sq ft. 
Lumen is a measure of how the human eye sees light. A lamp very high in the greens will have a higher lumen output than a different bulb yet they may indeed have the same PAR.

*awilson0001*
The good news is that with a good reflector behind each bulb and if you are only growing green water weeds, there are a large number of cheap bulbs out there that have a nice spike in the red portion of the spectrum and in the blue. I've even found nice "Daylight" T8 bulbs that grew plants very well. If you can build a wooden hood, then your options are numerous. A nice simple HO T5 retrofit kit can often be found on craiglist or online websites that will grow whatever you want.

If you need to buy a full light fixture as you don't want a DIY hood, then there are decent light fixtures out there you can find used or new.

Even if you want to keep the existing 2 separate lights, ahsupply.com also has some great compact fluorescent retrofit kits with amazing reflectors that might fit. Even those will be enough for certain plants planted directly under those 2 lamps.

Let me know what your options are and I can give you a good recommendation.


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## awilson0001 (Sep 2, 2010)

okay, the spectrum i am looking for is between 5500k and what? 10000k?

i see lots of tubes at the lfs and they all say good for planted tanks, but that included the 18000k i had and a lower one like a 2500k. so now i wonder what is the ideal spectrum?

i read that red and blue are the right color, but in freshwater, due to organisms or something, the color is actually green and yellow by the time it reachs the plants... ever heard this?

anyway, my acei like algae and i had a lot for them. i have removed those 18000k bulbs and am using my factory bulbs till i locate some better ones, but i noticed within days, the algae has turned dark. its black in some areas. is it actually dieing from lack of strong 18000k light?

i so need a happy medium so i can still have some algae for the acei and bushynose...

i cant find t8 36" in 6700k... any ideas?


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## Number6 (Mar 13, 2003)

*awilson0001*
the kelvin rating is a bit of an imaginary number. Someone looked at the color of the light and compared it to a chart and picked a kelvin number for the bulb. I'm not kidding... that is how that's done. So, 2 very different bulbs could have the same Kelvin number, or bulbs that are essentially the same but with some odd difference could have a completely odd Kelvin number.

E.g. many of the "12,000K" bulbs or "18,000K" bulbs are regular old bulbs with an "extra" dose of purple/violet or actinic (or both). You can easily have a bulb that is good for plants with extra.

So, what I tend to do is head to the local hardware shop and see what's there. I jot down the manufacturer and bulb model and go home to google the spectral graph for that bulb. If it's got a nice red and nice blue spike, I'm buying it. If there is nothing at the hardware store, I go shopping online.

F30T8/D Phillips is a daylight bulb that isn't great, but as long as you're not dabbling at the bare minimum light levels for the plants you want to live, you're set. At $5 it sure beats aquarium manufacturers that can hit $30 for a similar bulb.

Lighting choices will definitely affect algae. Very common is that change triggers the algae churning out spores. My guess is that this is what's happening in your tank right now. Good news is that if I'm right, it'll all come back with a vengeance!


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## nodima (Oct 3, 2002)

number 6 - great idea on the researching the spectral charts for hardware store bulbs. Never bothered to do that. Before I went compact florescent I used whatever plant and aquarium bulb sold at the closest Borg. All seemed to work quite well in my situation.

awilson0001 - as far as the plants/algae is concerned there is not a lot of difference between 6700 and 10K bulbs. Use which ever one or combo is pleasing to your eyes.


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## awilson0001 (Sep 2, 2010)

i did some research online as well, and have learned that the "k" rating is not a true light rating.

i knew that already, but it is used as a guide for the respective light spectrum isn't it? that's the way i understand it. if i am wrong, please tell me a better way. i want to know what to look for.

should i research the "nm" spectrum of a given light?

okay, good to know that 6700 through 10000 are close to the same.

what about the red and blue spectrum being altered to a yellow and green as it goes through the water to the plants in the wild? i am just wondering, cause bulbs i have seen that are around 6700 show high yellow to orange, not really red.

everyone says red for freshwater, but i cant find red it seems, just orange kinda.


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## Number6 (Mar 13, 2003)

*awilson0001*
I think you might be touching on the information that light doesn't penetrate water equally at all wavelengths. Blue penetrates deepest, red the least. The light isn't altered to a different wavelength I can assure you. I use LED lighting now and the red hits the bottom of the tank as red. 

The k rating is useful to know what package to pick up off the shelf and start reading 1st, second, third etc. I pick up 10,000K bulb packages first as they are more likely to have a good spectrum than say a 18,000K package. That isn't always true though, so for example... I really don't like the spectrum of corallife 6500 or 10,000K bulbs and I would rather walk away with a good 18,000K bulb than a corallife. If the 10,000K package doesn't have a good spectrum, put it back and pick up the next best K rating... :thumb:


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## awilson0001 (Sep 2, 2010)

WOW! HERES ANIN DEPTH ARTICLE ABOUT AQUARIUM LIGHT, KELVIN ETC.

I HAVE NOT LOOKED AT IT ALL YET CAUSE I DONT HAVE TIME JUST YET BUT IT LOOKS TO INTERESTING...

http://www.americanaquariumproducts.com/Aquarium_Lighting.html

I AM GLAD I STARTED THIS POST... LOTS OF GOOD INFO HERE THAT CAN NOT BE FOUND ANYPLACE ELSE I HAVE LOOKED.

OH AND SORRY BOUT THE CAPS.


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