# aquarium plant lighting



## yorkshire (Jul 27, 2004)

I've been keeping planted tanks for quite a few years and have always gone by trial and error. 
certain lighting would encourage algae blooms, certain plants would or wouldnt grow etc depending on the light conditions. so i decided to look into it a bit further.
This is how i understand the light spectrum, hope it helps, and feel free to comment if you disagree or i've got anything wrong :nod:

Wavelengths of light are usually measured in nanometres (nm)- billionths of a metre.
Light that the human eye can see ranges from between 380-700nm and is called the visible spectrum. At the 'short' end of the spectrum is ultraviolet (uv) light with a wavelength of 300-350nm and at the 'long' end is infrared light(700-750nm)
A light that appears blue produces more light at the lower end of the spectrum, about 400-500nm, while a light that appears red produces more light at the higher (650-700nm) end of the spectrum.

Sunlight peaks in the blue area of the spectrum and is used by both plants and algae.
Green light is reflected by the majority of plants and is therefore of little use to most aquarium plants.
Aquatic plants photosynthetic ability is most sensitive to red light between 650-680nm.
Infrared light (700-750nm) cannot be used by plants.

Chlorophyll ( a photosynthetic pigment) is used by the majority of plants for photosynthesis.
Chlorophyll 'traps' mostly blue and red light, although it is most efficient at trapping red light at around 650-675nm. Blue light is used just as much as red light simply because it is far more available and passes through water easier than red light.
I think it makes sense therefore that aquarium plant lighting should peak, ideally, in the red area of the spectrum. However in my opinion, this can produce an undesirable appearance. Artificial light with both a strong blue and red spectrum is usually more appealing and will still produce suitable light for plants.
algae prefer blue light, so remember that strong blue light will also promote algae growth. Aim for a balance between red and blue.
If you've got a basic understanding of physics, you'll know that the colour of an object is generated by the light reflected from it (not absorbed). The colour of a plants leaves can give a clue to its lighting requirements-

Light green leaves- indicates they absorb less light (reflect more) and contain less chlorophyll. Light green plants are likely to require bright light to compensate for their lack of chlorophyll.

Dark green leaves- indicate the plant absorbs less green light compared to light from other areas of the spectrum, indicating an abundance of chlorophyll. More chlorophyll means the plant can take maximum advantage of a given light source. Therefore dark green plants are generally better adapted to grow in low light conditions.

Red leaves- As previously stated, most plants photosynthesis best using the red part of the light spectrum. However the red colour of some plants indicates that they reflect the majority of the red spectrum. Thered colour of these plants is partly due to the plant using a less efficient cartenoid pigment to trap light energy rather than the usual 'green' chlorophyll pigment. These red plants need much brighter lighting with emphasis in the blue and green light regions.

My own trial and errors have shown that when my lighting is mostly provided in the blue region, plants grow ok, including the red ones. Trouble is i had quite a few problems with algae.
With a balance between the blue and red regions, plants grew ok and the algae problems reduced.
with an added light in the red region my plants grow amazingly quickly and there's next to no problem with algae, however red plants struggle or die so i can only use green plants. Also tank maintenance increases because surface and fast growing plants need pruning and cutting back to ensure they dont prevent light from reaching the smaller plants.

Hope this helps, i dont claim to be an expert and may be wrong in some areas of what i've written. It's just how i understand it at the mo


----------



## 33truballa33 (Oct 18, 2004)

nice info


----------



## phreakah (Sep 20, 2004)

wow, nice break-down...

thanks for the info! very useful


----------



## Gumby (Aug 13, 2004)

Have you tried dosing ferts high in Iron for the red plants? I've read that red plants use large amounts of iron.

Just as an FYI kinda thing, I've had best results using 10,000k bulbs. The plants grow like mad under them. The 10,000K spectrum is also visualy pleasing and provides very vibrant colors.

Also... Have you ever been able to keep Madagascan Lace plants alive? I've never heard of anyone being able to keep them alive for longer than 2 months. Whats the trick?


----------



## yorkshire (Jul 27, 2004)

i never used to bother with the names of plants, just gone by what they look like. so as to info on individual plants, i know very little apart from the ones that i've had in my setups.
Never realy tried many fertilizers either, just use the standard stuff from my lfs.
i've added a basic c02 system which seams to help, but i've read very little on this so cant offer advice on this topic either.
Thanks guys for all your info and advice








every bit helps


----------



## mr limpet (May 10, 2003)

yorkshire, unless you're lighting is more than 2 watts/gallon, CO2 isn't going to help. Nice treatise, BTW.

Ferts are a difficult game. Some plants need more of one thing, some need less, and it's difficult to keep up. I use substrate ferts only. It's way too easy to grow algae with inappropriate use of water fertilizers. The plants I use (swords, crypts, vals) are all heavy root feeders, so there isn't much need for water ferts.

I've always read that the best color temp. for freshwater plants is 5500K to 6700K. It provides the best balance for freshwater conditions. 10,000K is for marine environments, along with actinnic, as they are more suitable for the algal colonies needed by many organisms that depend on symbiosis with their particular algae. That's not to say that those color temps won't work... however I can't confirm or deny as I have only ever used 6700K lighting for my plants. I did 190watts in my 180 gallon with Amazon swords and they did great, until the nats were old enough to spawn and mowed them all down.







That was with 6700K lighting. I've done two watts per gallon in a twenty gallon planted that went wild... again with 6700K.

I constructed my lighting from these guys...

AH Supply

Good company, very helpful.


----------



## mr limpet (May 10, 2003)

Gumby said:


> Also... Have you ever been able to keep Madagascan Lace plants alive? I've never heard of anyone being able to keep them alive for longer than 2 months. Whats the trick?


 All the Aponogetons have a life cycle. They do go dormant for a period. They don't grow all year round. Some are more tolerant of water and substrate conditions, laceplants aren't.

Aponogetons are my second favorite plants, behind swords. They are generally suitable only for tall aquariums, though.

Try A. boivinianus. Very nice leaves, not lacey but nicely textured, and more hardy.
A. boivinianus
A. boivinianus


----------



## Husky_Jim (May 26, 2003)

My only objection to this valuable info is for the 'Red Plants' Vs Red Lighting.You can easily grow red-type plants with red-spectrum lights but you have to concider many additionall things (allready mentioned),like Co2 and proper fertilization!


----------



## yorkshire (Jul 27, 2004)

husky_jim said:


> My only objection to this valuable info is for the 'Red Plants' Vs Red Lighting.You can easily grow red-type plants with red-spectrum lights but you have to concider many additionall things (allready mentioned),like Co2 and proper fertilization!


Thanks Husky, it's possible to grow red plants under red lighting, it just needs to be especially bright, as a lot of the "red" light is reflected off the plants rather than absorbed. whereas if the red light is replaced by blue or green lighting, more light is absorbed, rather than reflected, and therefore the red plants will/should grow better.:nod: 
At least thats how i've been led to understand it. please correct me if i'm wrong









Thanks mr limpet, all contributions are apreciated. my setup is 47 gallons with 75 watts of lighting, the co2 has made a difference, although the biggest improvement was adding the 25watt red light, which also increased the wattage from 50 to 75watts. The extra 25 watts seems to have nearly doubled the growth rate of some of my plants :nod:

here's a pic of my setup :nod:


----------



## Mandy&Gal (Jan 13, 2004)

Great article but im not totally grasping the whole red light/blue light thing.

if the light operates in the 650-700 nm spectrum it will be red. does this mean i could go to walmart and get those party bulbs that are painted red to create red light, or would i have to go to a petshop and look at the reptile bulbs and read the package to see where that bulbs creates the most energy or what?

if anyone could clear this up for me a little better that would be great. I have a decent planted tank and the pants seem to be growing fine but i would like them to be doing great.

oh and awesome tank yorkshire


----------



## KrazyCrusader (Oct 26, 2004)

Depending on Tank size you need to buy a glass top then get a Light fixture, then get bulbs for it. Be picky about the bulbs and be more concerned with the LUmens then with the wattage. The more Lumens per Gallon the better. Bulbs with 3000 Lumens or so are pretty good. The bubls should be 6500K Bulbs. You can find them at many different places. I bought 2 bulbs from menards not looking closesly but they were only $5. I found out the bulbs I bought were only 2200 Lumen. I returned those Sylvania bulbs and went ot US Lamp and bought 2 really good T-12 GE bulbs. They produce like 3000 Lumens. Same Wattage. Much more efficient. 27% more light coming from the same size bulb. As you can see it makes sense to be choosy about bulbs.

York good article buddy!!


----------

