# effect of blacklight on aquatic plants



## Amazonaquascaper (Sep 20, 2015)

Ok so i wanted to talk about something that is irritating me..
I've search on the net for an answer but none could be founded its the effect of blacklight on plants
I will start the project myself to be sure of its effect on my plants...
It will consist of 3 main 'factors'
1st aquarium with fluores. tube and blacklight
2nd aquarium with only fluores. tube
&3rd aquarium with only blacklight
Project will take 3 months each month a different factor


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## second (Dec 21, 2005)

Is this for a nighlight?


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## Amazonaquascaper (Sep 20, 2015)

Its to show the rate of photosynthesis under blacklight...


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## Diana K (Dec 20, 2007)

The blacklight that I am familiar with is way up in the purple to ultra violet wave lengths, barely visible at all. High energy, so it makes certain things glow. Interesting Halloween effect. 

However, plants do not seem to use that end of the spectrum for photosynthesis. 
They can make pigments that are seen under UV light. Honeybees see into that range, and some flowers are marked with guides to show the bees where to get the nectar and pollen. 

My prediction:

Standard bulb (control): Will grow plants if other factors are right (ferts, CO2, right wavelengths in the light). 

Standard bulb + UV: No difference. 

UV only: (assume no ambient light- tank is wrapped so it only gets light from the blacklight). Plants will die. 

Side issue: UV is high enough energy to break the bonds of chelated fertilizers. You might monitor the tanks to see if this is happening. I do not know, however, if hobby level iron tests will show that or not. Also, I do not know if a UV light over the tank is strong enough to have this effect on all the water, deeper in the tank. This may be a non-issue.


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## Amazonaquascaper (Sep 20, 2015)

Was there anybody who's done this type of project to be 100% sure that the energy output from the blacklight would not increase rate of photosynthesis in plants??

Also does blacklight doesn't excites white pigment like teeth ,clothes,etc so how come there is no increase in the white light intensity of fluo. tube


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## Diana K (Dec 20, 2007)

I do not understand your question. Can you reword it or explain your idea behind the question better?


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## Amazonaquascaper (Sep 20, 2015)

A White cloth or any white object glowed in the dark when my father and i tested the bulb after researching on the net he said that the blacklight excites the particle in a white object to make it glow in the dark so how come it did not increased the light intensity of the WHITE tube by exciting their particles


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## Maryland Guppy (Mar 5, 2015)

Limited data out there for black light spectrum.
Only states <400nm. Reading has provided from 380 to 420nm.
Suspect that much in the correct spectrum would be in short supply.

Placed 6-3watt LED's at 385nm in my LED fixture.
Does it really help, who knows?
It only represents 18 watts of my 80 watt fixture.
The UV channel runs at full power 700mA.
At full capacity it is not a lot of lumens but is there none the less.

Interesting topic, I believe deficiencies will appear in the future.


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## Diana K (Dec 20, 2007)

> how come it did not increased the light intensity of the WHITE tube by exciting their particles


is this the question:

How come it did not increase the light intensity of the WHITE tube by exciting the particles inside the white tube?

Only an idea:
Perhaps the UV does not go through the glass of the white tube well enough to have a significant effect? 
Perhaps the white particles in the tube are not the right color to be excited by UV?


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