# is this too much light?



## coldmantis (Apr 5, 2010)

So I just got a 20 gallon long tank that was on sale at petsmart, now I'm going to upgrade my 10g shrimp tank to this one. So I will be making my own lighting with 3 23w cfl 6700k lights. Is that too much light, most likely the only plant I will have is riccia which I will be carpeting at least 70-80 percent of the tank, maybe some java moss and a few stem plants. I will have 1 2L diy co2. Previously in my 10g tank I have 2 15w cfl and I was getting really bad hair algae most likely due to overfeeding the shrimp. but now I got some cleaners baby bushynose plecos and some amano shrimp.


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## Darkblade48 (Jan 28, 2008)

In terms of lighting, it is definitely on the high end. 

I would use two bottles of DIY CO2 instead of just one, and to ensure that the output is as consistent as possible. Fluctuating CO2 levels are just as bad/can be worse than low CO2 levels.

Also, with that kind of lighting, don't forget that you will need to dose both macro and micronutrients.


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## waj8 (Jun 30, 2010)

It's not really that much light. CFLs have quite a few drawbacks. Thy don't work with high quality reflectors and they are not really that efficient compared to linear t5s. They also have rather short lives and not so good lumen maintenance. I would only put your lighting at a 3 out of 5. Still should be able to grow pretty much anything though. If you were to go with a 55 watt PC lamp with a good reflector it would probably provide a bit more light with less wattage. Fully understand though why you would go with the CFLs as they do cost a lot less in the short term and provide plenty of light.

In any case, you really need CO2 or Excel and proper ferts. to avoid algae with that amount of light. Hard to keep DIY CO2 steady with a small tank but it can be done.


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## Darkblade48 (Jan 28, 2008)

Another issue that you may have CFL bulbs is that they provide uneven lighting over the entirety of the aquarium. You may have higher lighting in the areas directly under the CFL, whereas you will have lower lighting at the extremities.


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## b.appel13 (Jul 29, 2010)

Also lighting in aquariums is so vague, Alot of people say watts per gallon but its more the lumens. You can have a 100 watt light and not high lumens. Also you have to take into consideration the depth of the tank. The majority of the beneficial light is taken out by the water. 

You can spend all day researching and still sit in the same spot or more confused. Alot of people say high lumens, others say high watts, others say the colour. 

Its all about trial and error for your set up. What plants, what tank, what substrate all that. If the current doesnt work, try something new until it does.


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## camboy012406 (Jun 11, 2010)

coldmantis said:


> So I just got a 20 gallon long tank that was on sale at petsmart, now I'm going to upgrade my 10g shrimp tank to this one. So I will be making my own lighting with 3 23w cfl 6700k lights. Is that too much light, most likely the only plant I will have is riccia which I will be carpeting at least 70-80 percent of the tank, maybe some java moss and a few stem plants. I will have 1 2L diy co2. Previously in my 10g tank I have 2 15w cfl and I was getting really bad hair algae most likely due to overfeeding the shrimp. but now I got some cleaners baby bushynose plecos and some amano shrimp.


that's too much light. just reduce to two 23w 6700k.


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## Darkblade48 (Jan 28, 2008)

Unfortunately, while lumens is a slightly better unit of measure than the WPG guideline, it is still inaccurate. This is due to the nature of what a lumen is (the intensity of light as perceived by the human eye). A bulb that possesses high lumens does not necessarily mean that it can be used by plants for photosynthesis.

As a result, what should be looked at is PAR (photosynthetically active radiation). Unfortunately, while PAR metres are available, they are in general, expensive, and not for regular hobby usage.

This is why more experienced users (myself not included ) can usually tell immediately whether a tank will encounter problems due to high light, etc.

More often than not, people still believe 3 WPG is required for "high lighting". However, with the advent of T5NO and even T5HO bulbs, 3 WPG would be overkill.


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## coldmantis (Apr 5, 2010)

for the reflector I'll be making another one of these
http://gtaaquaria.com/forum/showthread.php?t=16312
works pretty well for me considering that the other tank is 24" deep and I don't dose ferts especially on this one since it will be mainly a crs tank


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## waj8 (Jun 30, 2010)

With those lights it's impossible to design a decent specular reflector that will direct light toward the bottom of the tank. The best that can be done is to put them in a hood with a highly reflective white interior.

Calculating light levels is not that difficult as long as you discard the light spectrum from the calculation. The way it is done is to calculate the fixture efficiency using the same spectrum for all fixtures. Find the lamp mean lumens for your fixture if it had an 841 lamps in it. To do this just look it up in a lamp catalog multiply by the number of lamps and multiply by the ballast factor. Derate your fixture by 20% if it does not have a well designed specular reflector. Then you divide by the gallons. 70 lumens per gallon is a low light tank. 350 lumens per gallon is very high.

In this case it is obvious that the fixture will not be efficient. A 23 watt CFL only produces maybe 1200 mean lumens. Times 3 is 3600 lumens. The fixture must be derated by at least 20% because the of the shape of the lamps so you get 2880 lumens. Compare that to a 55 watt lamp with a good reflector which is going to be around 4080 mean lumens. Not really a heck of lot of difference but the point is the light level is lower than that provided by a good 55 watt PC fixture.


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## coldmantis (Apr 5, 2010)

my lumens for my 23w is 1600 each


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## waj8 (Jun 30, 2010)

That is likely the initial lumens. The initial lumens for a 55 watt lamp is 4800. You can do the calculation either way but keep in mind your lamps won't maintain that light level for long and you will have to shoot for a higher light level. Also keep in mind that you cannot compare two different spectra using lumens. Not much difference between a daylight lamp and cool white lamp though, so you can do it that way, but the results will be a little less accurate.


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## coldmantis (Apr 5, 2010)

I finally got some spare time to setup the new 20g long shrimp tank and finish making my diy light fixture here are the pics.

After a little paint










hope it reflects the light well










some wiring










computer powersupply style power input


















on/off switch










with flash










without flash


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## BettaBeats (Jan 14, 2010)

I really like the concept of this tank. How does that mound of sand stay in the peak/mountain shape?


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## coldmantis (Apr 5, 2010)

I use a squeegee, but it's only a day old so we're see how long that last.


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