# How do you encourage algae to grow?



## longtail4711 (Jun 8, 2010)

I know that sounds strange, but I'm trying to encourage the growth of soft green algae on some rocks to supplement food for my otos and pleco. 

I put some river rocks in a tupperwear with no lid, and put them in the windowsill three weeks ago along with some gravel that already had a little algae growth on it. 

Well, the gravel chunks are quite green now, but I'm not seeing anything on the river rocks yet. What can I do to encourage algae growth on these rocks?


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## Shotgun (Mar 1, 2009)

easy. feed a little more than you normally do, and provide a lot of extra light.


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## NursePlaty (Feb 5, 2010)

*Yep. Just boost up light wattage or longer photoperiod. Before I had pressurized CO2, I had a wattage of 3.45wpg and I had 20 species of algae growing.*


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## fishfish (May 27, 2009)

longtail4711 said:


> I know that sounds strange, but I'm trying to encourage the growth of soft green algae on some rocks to supplement food for my otos and pleco.
> 
> I put some river rocks in a tupperwear with no lid, and put them in the windowsill three weeks ago along with some gravel that already had a little algae growth on it.
> 
> Well, the gravel chunks are quite green now, but I'm not seeing anything on the river rocks yet. What can I do to encourage algae growth on these rocks?


Leave the lights on more than 8 hours a day, they'll grow everywhere.


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## TylerT (Jul 11, 2010)

is 15w good for a 10 gallon tank


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## Shotgun (Mar 1, 2009)

its a low wattage, but just keep the light on for more than 8 hours a day. try like 14!!!!!!!!!


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## fishyjoe24 (Jul 17, 2010)

TylerT said:


> is 15w good for a 10 gallon tank


very low light, also it depends more on p.a.r. and kelvins..then the 2-3 watts per a gallon rule.

PAR:

PAR is probably one of the most important considerations along with the related Useful Light Energy, Lumens per Watt, Focused Lumens and Watts per Gallon when choosing a light for your aquarium, yet is often over looked by both marine and freshwater plant keeping aquarists.

PAR is the abbreviation for Photosynthetically Active Radiation which is the spectral range of solar light from 400 to 700 nanometers that is needed by plants for photosynthesis. This is found from actinic UVA to infrared; 400-550nm (of which 465-485 has the highest PAR of the actinic range) which is the absorption bandwidth of chlorophylls a, c², and peridinin (the light-harvesting carotenoid, a pigment related to chlorophyll) and ~620-700nm which is the red absorption bandwidth of chlorophylls a and c².
Photons at shorter wavelengths (Ultraviolet –C or UVC) tend to be so energetic that they can be damaging to cells and tissues; fortunately they are mostly filtered out by the ozone layer in the stratosphere. Green light occupies the middle spectrum (550-620nm; what is mostly visible to us) and is partly why chlorophyll is green due to the reflective properties.
Bulbs that emit mostly actinic light will have a lower PAR (although actinic UVA still occupies an spike in PAR as seen from the graph and improve the PAR of your lighting), bulbs that occupy mostly the middle spectrum (yellow-green) such as “warm White (2700K) will produce little necessary PAR, while bulbs that produce mostly infrared will produce more important PAR (as seen from the graph), however it is the balance of infrared and UVA that will generally provide your best PAR output.

PUR (Photosynthetically Usable Radiation) should also be considered. PUR is that fraction of PAR that is absorbed by zooxanthellae photopigments thereby stimulating photosynthesis. As noted above, PUR are those wavelengths falling between 400-550nm and 620-700nm.

Light Kelvins
Kelvin is used in the lighting industry to define the Color temperature of a bulb. Higher color temperature lamps above 5500 K are "cool" (green–blue) colors, and lower color temperature lamps below 3000 K are "warm" (yellow–red) colors.

Kelvins as applied to color temperature of lights/lamps are derived from the actual temperature of a black body radiator, which is the concept of color temperature based on the relationship between the temperature and radiation emitted by a theoretical standardized material and termed a “black body radiator”. This is where the “classic” definition of Kelvin and that used for lights come together, as hypothetically, at cessation of all molecular motion (the black body state of this hypothetical radiator), the temperature is described as being at absolute zero or 0 Kelvin, which is equal to -273 degrees Celsius.

An incandescent filament is very dark, and approaches being a black body radiator, so the actual temperature of an incandescent filament is somewhat close to its color temperature in Kelvins.

Incandescent lamps tend to have a color temperature around 3200 K, but this is true only if they are operating with full voltage. When a lamp is dimmed below its full potential, its filament is not as hot, and it produces less light. The reduced temperature of the filament also reduces the color temperature downward. An incandescent light dimmed to 10% is considerably more red in color than one at 100%.

Another consideration as to the color temperature as applied to lights; color temperature does not take into consideration the spectral distribution of a visible light source. In cases where a light source, such as a fluorescent lamp, arc-discharge burner, laser, or gas lamp, does not have a spectral distribution similar to that of a black body radiator.

A few notes about Kelvin:
* Plant chlorophyll absorbs light at wavelengths of 300 to 700 nm (a Kelvin rating of about 6400 strikes a good balance here, which is why this is the best Kelvin temperature for freshwater plants and symbiotic zooxanthellae in corals).
* The lower the “K”, the more yellow, then red the light appears, such as a 4500 K bulb.
* The higher the “K”, the bluer the light appears, such as a 20, 000 K bulb.
*Higher Kelvin Color Temperature lights penetrate water more deeply, even more so in saltwater, however there is less of the infrared “PAR spike” as well. * The human eye sees mostly sees light around 5500K.
* Candle flame = 1850 – 1900 K
* Sunlight (1 hour after dawn) = 3500 K
* Typical summer light (sun + sky) = 6500 K
* Cool white fluorescent = 3400 K

mods you might want to make this a sticky! *old dude
HTH(hope this helped)


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