# light too close to the water?



## moneymark (Jan 11, 2013)

is there such a thing as your light being too close to the water? i have a ten gallon(12'' tall) with 2 (14w, 5000k, 800 lumen) cfl's about 3'' from the top. not sure if its too "intense" for some of the low-light plants like nana and java fern etc. I am new to planted aquariums so i apologize if its a dumb question.


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## amberoze (May 22, 2012)

It should beer fine. Just because a plant is labeled as lowlight, and does God in lowlight, doesn't mean it can't tolerate medium or even high light. There are some plants that actually can't tolerate higher lighting conditions. However, if you have taller plants or tall driftwood next to these light intolerant plants to provide shade, they should be fine. In my experience though, java fern and anubias (I assume that's what you meant by nana), can tolerate or even thrive in higher lighting conditions.

Sent from my Galaxy Nexus using Tapatalk 2


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## moneymark (Jan 11, 2013)

thanks for the quick reply. just set this tank up yesterday and just trying to catch any newbie mistakes early if i can. i dont have any shade for these plants really. if i notice them looking bad i guess i will have to make some.


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## GeToChKn (Apr 15, 2011)

I do 2x13W 6700k CFL's over my 10gals no problem, grows things fine, not too much to make algae. They work nice in the 10gal hoods.

what I did was take some that aluminum foil tape and taped all behind the lights, to A, protect the plastic a bit from the small heat CFL's do give off, and create a bit of a reflector in there, to at least bounce some of the light back. May not be super effective but even only bouncing back 20% light is still 20% more light. I took my time and applied the foil tape straight so it wasn't crumpled anywhere and gives a decent reflection.


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## moneymark (Jan 11, 2013)

yeah i dont have a hood i have two metal clamp on light fixtures that really reflect the light. Just hope i dont get algae and plants dont die. my excel will combat algae too i guess but thats a question for another thread. i am gonna build a stand and hood tomorrow and i'll raise the fixtures up a bit then.


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## amberoze (May 22, 2012)

moneymark said:


> yeah i dont have a hood i have two metal clamp on light fixtures that really reflect the light. Just hope i dont get algae and plants dont die. my excel will combat algae too i guess but thats a question for another thread. i am gonna build a stand and hood tomorrow and i'll raise the fixtures up a bit then.


With Excel, I have observed that regular dosing only combats algae in the beginning. Algae, like most all other living things, will eventually become tolerant of the Excel dosing and will grow anyway if the conditions are right for it. As it stands, I only dose Excel as needed. I've currently run out of Excel, but I do need to dose when I get a chance.lol


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## dmagerl (Feb 2, 2010)

In general, having the light to close to the top of the tank is not a good thing. A light that is up high off the tank will give a much more even light distribution across the tank.

Lets say the light is 3 inches from the top and the tank is 24 inches deep. If light intensity falls off linearly with distance, then 3 inches under water will be half the intensity as at the surface. 6 inches is 1/3 the intensity 9 inches is 1/4th intensity of the surface, and at the gravel it will be 1/8th the intensity as at the surface.

If the light is sitting 24 inches above the surface, then the intensity at the gravel will be only 1/2 the intensity as at the surface. So it is much more uniform throughout the depth of the tank. 

You will be much more likely to get algae in the upper portions of a tank due to high light conditions if the lights are sitting on the tank.

I raise the lights up for this reason as well as it just makes it sooooo much easier to service/clean the tank if you arent continually bumping into a light fixture.


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## moneymark (Jan 11, 2013)

are you saying to put my lights a foot above my tank? thats a big no-can-do.


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## dmagerl (Feb 2, 2010)

Not saying you need to do anything. Loads of people have lights sitting low down and have no problems. I'm just saying in general, its better to move the lights up higher to provide a more uniform light level.

If you start seeing algae in the upper levels of your tank, its something to keep in mind.


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