# light wattage to water depth and the effect on growth



## EDGE (Feb 28, 2004)

Will the growth rate on plants using a 15 watt bulb (3" away from water surface) with a water depth of 3" similar to a PC (3" away from water surface) with a water depth of 18"?

To control the variables, the growing point we are looking at is right at the bottom depth and not near the water surface.


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## MiamiAG (Jan 13, 2004)

EDGE,

Not sure if I'm answering your question, however, I think it depends on the plants, the intensity of the bulbs, and the reflector being used. I never think about light at water surface. Instead, I'm more concerned to get the right amount of light to a specific plant at the leaf surface.

As a secondary matter, I worry about how the specific light impacts the overall look of the aquascape to the viewer. Sometimes, this is just as important.

To summarize, a 15w NO bulb may be enough to adequately grow some low light Crypts. However, a more intense power compact would be better for H. zosterifolia growing in a CO2 supplemented environment.

HTH.


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## EDGE (Feb 28, 2004)

oops, I should have said, leaf surface and not water depth.


Ignore the 3" away from water surface. Assume they are the same distance away from the water surface.


Is the growth rate of a 15 watt bulb reaching the surface of a leaf at a 3" depth be similar to a 55watt PC reaching the surface of a leaf at 18" depth?

Another word, To what extent does water depth have a huge impact on lighting requirement when growing plants submersed?


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## Justin Fournier (Jan 27, 2004)

Edge,

Assuming the water is clear without particle matter, I would venture a guess that not much light is lost as it passes through the water. So I think x plant needs y amount of light to reach it's surface, so the more things you have impacting the light's travel, the more light you need to make up for what you lose.


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## Daemonfly (Mar 21, 2004)

Theres a similar thread over at The Planted Tank that should be of interest: http://www.plantedtank.net/forum/viewtopic.php?t=5768


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