# Window screen light filter



## Hoppy (Dec 24, 2005)

Another way to look at this is, if you are getting high light with your fixture, and can't remove a bulb and still run the fixture, and can't raise the fixture, or don't want to, putting one layer of this window screen on top of the tank or over the bottom of the light, will reduce your light to medium intensity. Two layers will reduce the light to low light.


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## Wasserpest (Jun 12, 2003)

Good info, but...

I'd suggest to always look into lower wattage bulbs or less bulbs first. To me, adding window screening or covering up bulbs or even raising up fixtures seems environmentally irresponsible & wasteful. Not to mention energy bills and added heat output.

Reducing the light period is another option for new tanks if you want higher light levels later on.

Best is to run your tank with the minimum amount of light necessary to get sufficient plant growth.

Just my opinion... I know others think differently. :smile:


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## jjp2 (May 24, 2008)

you are right, Wasserpest. But if you already have the light and bulbs and can't get lower wattage bulbs, Hoppy has a great easy solution.


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## Hoppy (Dec 24, 2005)

There are a few advantages to having the light hanging a foot or so above the tank. First, it lets you get your hands in the tank easily, so you tend to do more of the day to day maintenance that is so necessary to keep algae away from the tank. Second, the higher the light is above the top of the tank, the lower the intensity at the top of the tank. Otherwise, any tank with a light sitting on the top, has high light intensity at the top. Remember, the sun isn't right on top of our gardens, it is raised quite a bit, so the light intensity is the same from the soil up to the top of even Jack's famous beanstalk. That must be good design technique?:smile:

But, no question that it does waste electricity.


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## volatile (Feb 13, 2007)

Thanks Hoppy. I appreciate you taking the time to perform these experiments and post about them. It will definitely help me out when I have a tank where I can suspend the lights.


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## barbarossa4122 (Jan 16, 2010)

I am heading to HD to get that screen. Thanks a lot for the info Hoppy.


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## happi (Dec 18, 2009)

i have used this method in the past, did not like the lights becoming dim, its not good for those who prefer brighter light.


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## OverStocked (May 26, 2007)

happi said:


> i have used this method in the past, did not like the lights becoming dim, its not good for those who prefer brighter light.


The whole point is to dim the lights....


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## happi (Dec 18, 2009)

OverStocked said:


> The whole point is to dim the lights....


in that case wouldn't people just use PC lights which will produce brighter light while keeping it at low/medium light? 

this is what i got from using T5HO: http://www.plantedtank.net/forums/algae/145117-never-ending-algae-spot-algae.html

i know many people are going to argue about T5HO being better but i haven't found anything good about it beside reduce in monthly bill.


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## OverStocked (May 26, 2007)

I think we're missing the point.... This would be to reduce the intensity if lights you already have or if you had to light odd size tanks.


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## happi (Dec 18, 2009)

OverStocked said:


> I think we're missing the point.... This would be to reduce the intensity if lights you already have or if you had to light odd size tanks.


i know the point, but IMO reducing the light intensity by using window screen also reduce the brightness, when you could still have the brighter light without using the window screen. am talking about using PC bulbs which are brighter but give you almost the same results when you reduce the t5 lights with window screen.


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## OverStocked (May 26, 2007)

Perhaps I am missing something, but how do you get "brighter" light will reducing par? 

I think perhaps you are confusing color temp, which could be done with any light configuration. Or perhaps your experience with PC bulbs involved a whiter spectrum than the bulbs you've seen in t5ho. 

I do not know of any way possible that light could actually be "brighter" while being less intense. 

"brightness" is either a reflection of color temp(which can be changed with any type) or par. Either way, the connection to PC bulbs being "brighter" doesn't make any sense.


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## happi (Dec 18, 2009)

OverStocked said:


> Perhaps I am missing something, but how do you get "brighter" light will reducing par?
> 
> I think perhaps you are confusing color temp, which could be done with any light configuration. Or perhaps your experience with PC bulbs involved a whiter spectrum than the bulbs you've seen in t5ho.
> 
> ...



all i could say is that i had 6 wpg of PC 6700K over my 20g in the past and there were no algae issue and tank looks 10x brighter than compare to my 50g tank which have 2x54w T5HO bulbs 6700K. no matter what i do in this tank, plants are always covered with black spot algae, i can take off the algae simply by rubbing it but i cannot do this to the whole entire tank. i never had this problem with the PC lights. all am saying is T5HO even at dim lights cause these problems for me, the whole purpose of reducing the light is to reduce the algae. isn't it? why make the lights look dim when you could have brighter lights while keeping the algae away with PC type bulbs. 
its is also in Hoppy's light comparison chart, where PC is still considered low light while having very high wattage compare to T5.


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## OverStocked (May 26, 2007)

Without a doubt, you are seeing an optical illusion or perceived difference that is not reality. 

The light comparison you mention is the point that PC lights are low efficiency, nothing to do with brightness. What it means is that T5HO has more output per wattage. And by more output, "brightness" would be par. It is not that it somehow is brighter but has less usable light. 

To further understand, compare incandescent lights. 100 watts of incandescent is even less efficient than PC or T8. 

The reason your PC lights had less algae is simple. Less efficient bulbs and reflectors. 

too much light, too little co2, and too little ferts are the cause of algae, 99.5% of the time. Once algae is established ina particular time, the time it takes to eradicate it can be very long.


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## redfishsc (Aug 29, 2010)

There are some times that lower PAR can appear "brighter" to our eyes than some "higher" PAR situations, but it's never comparing apples to apples and there are always intervening variables that make a mess of trying to predict it. 

My 11g and 45g are both LED lit but using very different LED combos and driven at different drive currents. 

The 11g has a PAR of about 30 on the sandbed and it appears quite bright to my eyes. Yet my 45g, which also has around 30 on the sandbed, looks pitifully dim. 


I'm not entirely sure of why this is. If I crank the LEDs up on the 45g such that it looks bright to my eyes, I get algae hell.



I'm not sure how "green" registers on a PAR meter, but our eyes are way more sensitive to green light than plants are, so a green light that's ludicrously bright to us may not be all that useful to a plant. You'd think that this means "lower PAR" on lights high in the green area, but this is just a guess.


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## wespastor (Dec 20, 2009)

One benefit that I use the window screen for is to shade part of my tank from the High light that some of my plant like / need and give my low light fish a place to hide from it.

Best wishes,
Wes


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## barbarossa4122 (Jan 16, 2010)

I am so pleased I bought the window screen the other day, thanks to Hoppy. And, according to him I reduced my lights about 30 to 40%. My 55g is looking a little dimer now but, who cares. Btw, I use 2 54w Geisseman on this tank, about 10" from top of tank.


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## sayurasem (Jun 17, 2011)

Hi guys, I found this thread so I just continue here...

Something is odd about the spectrum of my Finnex 36" LED light using the window screen. And I just notice I bought the grey instead of black screen. Do you guys think its because I'm using grey screen the light spectrum went out of wack like this?










Two screen *on*









Two screen *off*


















The same thing happened when I only use 1 screen.


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## Hoppy (Dec 24, 2005)

It looks like you are getting a diffraction effect that makes those bars of light show up. I haven't tried the screen with a LED light, so it may not work the same way. All I know is how it works with fluorescent lights. But, when you start shining light from near point sources through any form of "grating" you can get unexpected results (unexpected only to a non-physicist).


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## somewhatshocked (Aug 8, 2011)

I've been using black screening with Finnex fixtures and it works well. Takes 2-3 layers to accomplish what a single layer can do with a regular bulb-type fixture, though.


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## sayurasem (Jun 17, 2011)

somewhatshocked said:


> I've been using black screening with Finnex fixtures and it works well. Takes 2-3 layers to accomplish what a single layer can do with a regular bulb-type fixture, though.


Do you get the light bars like I did?


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## somewhatshocked (Aug 8, 2011)

Nope, no bars.

What does your fixture look like when you place it over your tank while using the screening? Still get the bars?


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## beedee (Jul 1, 2010)

I have an AquaticLife 36" T5HO with one 6500k bulb and one Roseate bulb, I'm using 3 layers of the gray screen over my 12g Long. I'm only using the stock legs that came with the light to elevate it above the tank, so at it's highest point, the light is about 14" above the substrate, and at the lowest, about 8".

The tank has only been filled for one week, but so far so good. I'm debating on removing one layer of the screen. My photoperiod is 6.5 hours right now. 

Thoughts?


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## rcs0926 (Jun 14, 2013)

Hoppy said:


> We have been recommending using ordinary window screen to reduce the light intensity when you can't raise the light fixture high enough, but I had no idea how much the reduction would be. So, I bought a roll of fiberglas, black window screen from Home Depot, less than $5 for a huge piece, and tested it with a PAR meter on two tanks with two different lights.
> 
> Here is what I bought:
> 
> ...


Ran into this thread after Googling "window screen aquarium light". Thanks for this info Hoppy. You mentioned in another thread that I created today that window screening would reduce light intensity by 40%, and it's good to find the source of your numbers.


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## rcs0926 (Jun 14, 2013)

I'm going to try using one layer of screening and see how that works out. If the lights need to be dimmed even more, then I'll add another layer or two.


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## nate2005 (May 29, 2013)

How has everyone attached it or are you just placing it on the aquarium glass top? 

Sent from my SCH-R530U using Tapatalk 4 Beta


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## GadgetGirl (Oct 11, 2013)

nate2005 said:


> How has everyone attached it or are you just placing it on the aquarium glass top?
> 
> Sent from my SCH-R530U using Tapatalk 4 Beta



Reviving an old thread. I'm curious about this too.


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## jeffkrol (Jun 5, 2013)

GadgetGirl said:


> Reviving an old thread. I'm curious about this too.


Get a "kit" like this and make screens to any size.
http://www.midlandhardware.com/875658.html?gclid=CNDK6-7WkcYCFQiBaQodKboAIQ#.VX7CFLGrPO8
You can make one the size of the top or one the size of your light..
Attaching it to the light is nothing more than strapping it to it..

Strapping it on the light face (or slightly suspended below, and made oversize to compensate for the light spread) would probably be preferable from a maintenance standpoint, unless you are doing open top and can use the screen as a top.

More depends on aesthetics and how hot your light is...


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