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beencees

Lets clear things up. Some facts about lighting.

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Ok, let’s clear up a few things about lighting in the aquarium.

Note: being that i am a self confessed plant nut this information is more specifically biased towards planted tanks however no doubt there will be information that may be useful to others.

KELVIN:

Firstly, the most common thing people are told to look for in a “good plant light” is the Kelvin rating (that’s the “K” you always see after a number, eg 6500k). This is a bit misleading to be honest although it is partially true.

The Kelvin rating of a light refers to its colour temperature. Although it’s true that a higher Kelvin rating will have more blue light and a lower Kelvin rating will have more red light it is not actually an indication of what wavelengths of light may be present, more an indication of how the light will appear to us (humans). You can have two different lights with the same Kelvin rating but the wavelengths of light actually produced can be completely different.

So what do you need? Well, for optimum leaf development you want light in the blue spectrum, for stem elongation light in the red spectrum and for it to look “nice” to us light in the green spectrum.

If you’re tank looks really bright and your plants seem really green it just means that your light is producing strongly in the green spectrum. Don’t be fooled into thinking that this bright light means you’re plants are going to grow like crazy though because plants don't use light in the green spectrum for photosynthesis so for them it’s not much use.

A “full spectrum” plant light is commonly referring to a light that has a colour temperature between 5000-6500k but this does not indicate what wavelength in nanometers the light is actually emitting and this is what really matters.

So what you need is light that peaks at the correct wavelengths for photosynthesis and carotenoid production. Those wavelengths are:

Chlorophyll-a: 430nm/662nm

Chlorophyll-b: 453nm/642nm

Carotenoids: 449nm/475nm

The lower numbers are in the blue spectrum, the higher ones in the red spectrum. Red pigmented plants use more light in the blue area of the spectrum.

The point of all this is that you don’t need to get carried away with what colour spectrum to look for in a light, more what wavelength peaks the light produces. Use the colour spectrum to decide how you want the tank to look to YOU. So a red colored light will enhance red fish and plants, a blue light will enhance blue fish and a green light will make the tank look bright and the plants look green.

LUMENS & LUX:

These are both very similar as Lux is just lumens per square metre. They are both also pretty useless as far as determining how good a light will be for plant growth. Lumens are just a measure of how much light energy is produced as perceived by the human eye. After reading the above you can already see that most of this light is going to be in the green spectrum so it means little to plants and in fact as a result good plant lights are often not particularly bright. If you look at two lights of the same wattage and one has a much higher lumen rating then you know it’s producing alot of light in the green spectrum. So in a nutshell the lumen rating for a plant light is of little importance.

PAR:

This is another often misunderstood area of lighting.

PAR stands for "Photosynthetic Active Radiation". People who understand the irrelevance of lumens often look to this as a more accurate sign of a lights brightness and suitability to a planted tank. PAR measures all light output between 400nm and 700nm so it actually encompasses the wavelengths that are useful to plants and not just light in the green spectrum as lumens does. This will give you a more accurate idea of how much useful (to plants) energy is being produced. Again though this is not entirely accurate as there is still alot of light energy being produced that is of no use to plants. The only real rating that will provide you with JUST information on the wavelengths that matter to plants is PUR (Photosynthetic Usable Radiation) which measures only the energy produced in the red and blue spectrums.

If you have read this far, firstly congratulations :humble:There is plenty more that can be said on this subject and others alot smarter than me may wish to do so. However, hopefully all of this has given you a better understanding of what really matters and what to look for as far as lighting goes and cleared up alot of the misinformation that gets floated about.

Thanks for reading.

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Soooo what brand do you use? Or which light is good in your opinion please?

I wont pretend that i have tried every tube that's on the market but i have a combination that i have found very effective.

I use T5 lighting and run one Sylvania Grolux for every one Fluval Life spectrum (formally Hagen Life Glo). So in a quad i use two of each. I have tried various other tubes including Giesemann. Some perform "ok", others are more suited to algae farms. The Sylvania/Hagen combination has grown every plant i have ever tried with great success.

Often it takes a combination of two different tubes to get the ideal balance between excellent plant growth and pleasing visual aesthetics.

It's worth noting though that as with most things in this hobby there is no one correct answer to any given question. Every tank is different so there are sure to be other combinations that work very well also.

Edited by beencees

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Just a word on LED lighting.

There is a misconception that i am very anti LED. This is totally untrue.

I have been in this game for a very long time and have watched the advent of LED's with much interest for many years. I am more than keen to use them however i will not just blindly let salespeople talk me into things without doing my research. Despite what many have tried to have me believe i have found time and again that their claims are, at best, greatly exaggerated. People have touted the virtues of each latest and greatest to me and then later admitted their initial enthusiasm was unfounded and the hype was not lived up to.

I have watched the fads come and go and waited for the "real deal" (as far as planted LED's go) to come along. I have been patient but have now decided i will do some experimenting of my own and see what type of results i can get.

I have a DIY set up in progress (i do love DIY'ing) and will shortly be purchasing some of what appear to be the more proven LED units available.

I sincerely hope i will have tremendous results and may perhaps do a thread on things in the future.

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Just a word on LED lighting.

There is a misconception that i am very anti LED. This is totally untrue.

I have been in this game for a very long time and have watched the advent of LED's with much interest for many years. I am more than keen to use them however i will not just blindly let salespeople talk me into things without doing my research. Despite what many have tried to have me believe i have found time and again that their claims are, at best, greatly exaggerated. People have touted the virtues of each latest and greatest to me and then later admitted their initial enthusiasm was unfounded and the hype was not lived up to.

I have watched the fads come and go and waited for the "real deal" (as far as planted LED's go) to come along. I have been patient but have now decided i will do some experimenting of my own and see what type of results i can get.

I have a DIY set up in progress (i do love DIY'ing) and will shortly be purchasing some of what appear to be the more proven LED units available.

I sincerely hope i will have tremendous results and may perhaps do a thread on things in the future.

what would be the best light for a 6x2x2 African display with white sand substrate? I want it to look really fresh and pop. I just have a ****ty 4 foot on it now that came with the tank.

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