# Using Window Screen to Filter Light



## aceranch (Dec 21, 2013)

I use short pieces of black electrical tape to cut back light sometimes.


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## someoldguy (Feb 26, 2014)

I tried it and I didn't think the percent reduction was that great .Didn't try 2 pieces , but I guess the reduction would be double as long as the meshes aren't aligned . What I ended up doing was using a piece of 1 stop ND film which cuts the light by 50%
( 1 stop in photography represents a halving or doubling of the light reaching a camera's sensor) Did this to the Planted Plus on my 45 and so far it's working OK . Just taped it over the plastic covering the LED's . Here's the stuff I used ...https://www.bhphotovideo.com/c/product/163139-REG/Rosco_102302092124_E_Colour_209_3_Neutral.html
It's basically a grayish tinted very thin plastic , almost like cellophane . Cuts with a scissor .


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## xmas_one (Feb 5, 2010)

Are you sure dimming the light with window screen is the best solution for your problem?


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## DHFisher (Sep 3, 2017)

Not 100% sure Xmas_one but I have been experimenting the last two months,with the 24/7 lighting, algae builds up in week. With lights on 10 hour timer with 20% lighting setting, little to none. I have read that the lighting output can change as the light ages. Not sure if that is true with leds or not.

Vacuum the whole tank after throwing out the plants over a two week period. Made sure I don't feed the fish much. Vacuuming portions of the tank every two weeks and not much is coming like when I did the major cleaning. 

So giving the lighting a go. Plus will be adding an aerator to try to help bring back up the pH. After that, maybe a small bag of crushed coral.

Someoldguy, thanks for ND film info. I'll check that out.


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## AbbeysDad (Apr 13, 2016)

When I first converted my well established 60g to a planted tank (after receiving my Finnex Planted+ 24/7), I had a lot of green algae. I used window screen on the canape beneath the light for several days. I don't know the exact amount of light reduction, but it sure helped. The algae outbreak was really temporary as in time, as the plants grew and nutrients became more balanced, algae became much less of a problem. Goes to show how a fish only tank, even with weekly partial water changes can contain excess/unwanted nutrients. It just took more light for the algae to go wild.

Note: In addition to less light (with the shade screen) While I scrubbed the algae elsewhere, I let the algae grow on the one side wall behind a bubble bar...acting as an algae scrubber. (Letting the algae grow somewhere uses the excess nutrients and indirectly inhibits it's growth elsewhere).


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## Wantsome99 (Nov 27, 2016)

Finnex 24/7 are bright lights for low tech. I have one on a non planted 40 gallon and my tank became an algae factory also. 10 hours is a long duration for a low tech. Low tech plant growth is limited because of no co2. You need to find a balance between brightness of the lights and growth of plants. Believe it or not you don't need a lot of light to grow plants. A single flourecent tube is enough light to grow most easy plants like ferns anubias and crypts. LED lights are tricky in low tech. The diodes are very focused and the light isn't evenly spread out as it is with a florescent tube. 

Dim your light down very low and see how things grow. Then work your way up in brightness. If algae grows on a plant it blocks the plant from photosynthesizing and absorbing light. If the plant can't photosynthesize it can't grow and out compete algae. 

Floating plants are also a good option they block light and soak up extra nutrients. Except floating plants can be tricky with led lights. Because you don't get an even light spread near the surface of the tank.

I would dim the light way down and stick to 7 or 8 hours of lights on. If you really want to diffuse the light wax paper works also.


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## AquaAurora (Jul 10, 2013)

I've used a few layers of window screen over finnex lights on my marimo tank (doesn't need much light), as well as the finnex 24/7 on my husband's 12g long. I've not had hair algae issues with this. I'd also put lack electrical tape over ever-other led on the light for the marimo tank (along with window screen


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## AbbeysDad (Apr 13, 2016)

Wantsome99 said:


> Finnex 24/7 are bright lights for low tech. I have one on a non planted 40 gallon and my tank became an algae factory also......


I tend to disagree. For most low tech tanks, I think the 24/7, running in 24/7 mode would be great. Because I have a 24" depth on my 60g, I take mine out of 24/7 from 10am - 3pm and run in max or a custom of max white / max red, then put back in 24/7 mode. Plants do great, algae is not a problem any more. Lots of fish and limited ferts.
I would agree that if you ran the 24/7 on MAX for 14 hours, it would be too much. I'd also agree that if you put any [new] light that supports plants on an established tank, there's bound to be an algae issue until balance is achieved....but once you get there, it's a beautiful thing!!!


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## Wantsome99 (Nov 27, 2016)

AbbeysDad said:


> I tend to disagree. For most low tech tanks, I think the 24/7, running in 24/7 mode would be great. Because I have a 24" depth on my 60g, I take mine out of 24/7 from 10am - 3pm and run in max or a custom of max white / max red, then put back in 24/7 mode. Plants do great, algae is not a problem any more. Lots of fish and limited ferts.
> I would agree that if you ran the 24/7 on MAX for 14 hours, it would be too much. I'd also agree that if you put any [new] light that supports plants on an established tank, there's bound to be an algae issue until balance is achieved....but once you get there, it's a beautiful thing!!!


Judging by your 60 gallon your doing quite well. I've been at this for 10 years and can't achieve what you have with your 60 gallon. I have a 40 gallon 36"x12" tank with my finnex 24/7. I only run the lights 8 hours and it turned into an algae factory.


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## AbbeysDad (Apr 13, 2016)

Wantsome99 said:


> Judging by your 60 gallon your doing quite well. I've been at this for 10 years and can't achieve what you have with your 60 gallon. I have a 40 gallon 36"x12" tank with my finnex 24/7. I only run the lights 8 hours and it turned into an algae factory.


As I mentioned, when I first put the 24/7 on my well established tank, I got A LOT of algae. I believe the nutrient levels were such that the increased light just caused an explosive algae bloom. As I mentioned, I let the algae grow on one wall behind a bubble bar as a pseudo algae scrubber while I kept the other glass clean. This and backing off on the light some....and as plants grew, algae became less and less of an issue. I think for many low tech tanks (less than 24" deep) the 24/7, running in 24/7 mode would work just fine. With my 24" depth, as I wrote, I take mine out of 24/7 from 10am - 3pm and run on either max or bright white/bright red, then back to 24/7. Works for me.
An alternative (Although I'm not a fan of gluteraldehyde) for a newer setup might be to dose with Excel or Metricide to keep algae in check as plants grow and use up the excess nutrients.

To the OP - how are your tank nitrate levels and have you checked your source water for nitrates???


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## iliketogolf (Feb 7, 2010)

DHFisher said:


> How much light does 1 layer of screen cut out? Does that filtering double if you add two layers?


 
I am having the same issues in a newly set up tank. My 24/7 SE is 24 inches above the substrate but it's too much light for a low tech setup and I have too much algae. I need to cut back on the light but love the convenience of the 24/7 mode. Been thinking about putting window screen on the glass top. Has anyone calculated PAR values with the added element of a window screen to see how much light is decreased?


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## milesm (Apr 4, 2006)

check this thread out http://www.plantedtank.net/forums/10-lighting/1210970-dimming-feature.html. pretty sure the first one jeff linked works seamlessly with beamswork leds, might have to do some diy with finnex.


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## OreoP (Aug 12, 2016)

DHFisher said:


> How much light does 1 layer of screen cut out? Does that filtering double if you add two layers?


I do not have exact numbers but when setting up my 135gal, I ran into algae and green tank issues using T5HO fixtures. I used a window screen on top of the tank, about 4-5 inches from the light and saw a LUX reduction of about 30% with the screen.

Once the tank was filled with plant growth, I removed the screens with no adverse effects.


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## CT_Ram (Sep 10, 2017)

I have used mosquito net to lower the light for a while until the plants were fully growing and prevent algae. Or even if I add new fish so they fell more comfortable for a few days. I prefer to lower the light than to reduce the photoperiod. I know that plant people are ok with having landing strip lights ON for only 4h a day. But I think the fish would appreciate lower light and ON for 12h that is how many light hours there is near the equator from where most of the fish are. And on top of that I can look at the fish tank. Don't kill me! I know I am in a plant forum  and reducing photoperiod is the first thing people recommend here.


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