Seeking Enlightenment about Lighting

The first time I got serious about lighting, in the 1980's, I had a 125 Gallon aquarium in my living room, and I had twin 175 Watt Metal Halide lights suspended from the ceiling, I had a Dupla CO2 system that was completely automated (controlling the pH at 6.8), a wet/dry filter and a large Eheim Canister filter. I had done everything in that tank so that, with an automatic feeder in place I could travel for two weeks and never worry about the tank. The tank was heavily planted with jungle val along the back wall, and a big piece of driftwood in the middle, and plants everywhere. Still, I was not as much on top of water quality as I am today. Which is not to say I don't make mistakes. I do. Yet, I stay focused on just learning as much as I can about what is going on with water chemistry, and the ecological balance between plants and fish.

Lighting a 29G tank: 30" x 18" x 12" - deep!

Lighting is key, that much is clear, but I am a long way from being totally clear about lighting. I did come to the conclusion very quickly that the traditional hood that came with my main 29G tank was not enough, and besides switching the fluorescent to a Hagen Flora-glo, I also added a Marineland "hidden" LED, and I actually run a 3Watt LED floodlight as well (Deep Blue Solar Flare 3W). now I am in observer mode as to how the plants are doing. Generally speaking they do fairly well, and I'm not going too crazy with ferts, but typically once a week I add some Excell, some Iron, and some Potassium, and maybe a little flourish. With that regime and fairly easy plants the results have been fairly good, but I want to do some experimentation to see what works better.

To begin with I'll be adding a Hydor CO2 Green NRG Advanced, It is a discontinued product, and they are being sold out... the reviews are mixed, but to me it seemed worth a try because I've taken a liking to Hydor products. Time will tell how well this works out. Online I can get 74G CO2 canisters for $20 for 2, so that should probably last me for a year. Worth a try. And if it does not work out, I'll have to get a serious CO2 system... the reason to mention it here is the better your lighting, the more your plants need CO2 to sustain growth.

So, back to the lights. Some of the best sources of information about lighting are:

• Aquarium Lighting page on AAP. Always a favorite.
• Planted Tank forum on Lighting. A treasure trove of discussions!

 Here is the configuration of my 29G tank:

• Main hood: Hagen Flora-Glo, 20W, 2,800K, 650 Lumen, or 32.5 Lumen/Watt
• Additional: Marineland Hidden LED 21",  6,500K (72x .06W white LEDs, and 16x .06W 460 nm blue LEDs), PAR/Lux at 12" 25/1121, and at 24" 11/377 
• Spot light, Deep Blue Solarflare 3W Micro LED 6,700K

29Gallon tank as of June 20th, 2016

As an alternative for the main tube, I also have a Hagen Life-Glo tube, which is 6,700K, and I may try to alternate those two for like 2 months at a clip, to see if I can tell the difference. It definitely has a much higher light output, at 1,470 Lumen, or 73.5 Lumen/Watt.

In the end I suspect I may get hunches, but you'd have to engage serious light meters to tell the difference. Most importantly, with the above combo I have barely a hint of algae, certainly not to any problematic levels. I may wipe the glass clean with an algae sponge once a month. Note that I do have Duck Weed and Hornwort, which are surface (Duck Weed), or floating (Tropical Hornwort), plants that tend to filter the light.

As I'm still struggling to understand all the parameters, and have precious few means to monitor them exactly, let me try to put some order to the mess:

1. Color "temperature," this is important as it relates to the absorption of light by the plants. Notable that the higher K lights (14,000K & higher) penetrate deeper, but may cause too much algae, and therefore should usually be avoided in planted tanks. You might however be able to combine a 2,700K light with a 6,700, or even a 18,000K light.
1. 2,700-2,800 Kelvin is usually known as 'warm white,' and it's sort of the temperature of an incandenscent bulb. It seems to be decent for plants, hence Hagen's "Flora-Glo" is 2,800K.
2. 6,500-6,700 K is the color temperature of the sun at high noon, and offers the greatest depth penetration, and in general seems to do well with plants, note that this is the color of Hagen's Life-Glo and also of the little spot light I have in my tank.
2. The Nanometer range (note that the yellow and green is not well absorbed by plants, which is why we see those colors so well). Note that many lights will display on the package what range they put out:
1. 400-420 nm: Violet
2. 420-440 nm: Indigo
3. 440-490 nm: Blue
4. 490-570 nm: Green
5. 570-585 nm: Yellow
6. 585-620 nm: Orange
7. 620-780 nm: Red.
3. Lumen the quantity of light, and LUX is light intensity, one LUX being one Lumen per square meter.
4. PAR stands for Photosynthetically Active Radiation, and generally the range of 400-700 nm, which is the part of the light spectrum that is most helpful to plant life. You need a special meter to  measure PAR, called a Quantum Light Meter.
5. RQE, PAS & PUR - Quality of Light, Useful Light Energy.
1. PUR (Photosynthetically Useful Radiation).
2. PAS (Photosynthetic Action Spectrum).
3. RQE (Relative Quantum Efficiency) indicates the efficiency of photosynthesis.
6. Watt equals one joule of energy per second. People used to talk about watts per gallon, but the term has lost all meaning because of today's lighting options.
7. CRI (Color Rendering Index) has to do with the appearance of the colors, and a normal incandescent bulb has a CRI of 100.
8. UV - Ultra-Violet Light - has little to do with the issue of plant growth etc., but everything with the health of aquarium water. As per usual, my favorite source of information is this article on UV-C Sterilization on the AAP website. Do you need UV? Apart from all of the technical discussions, note that in nature, water would receive plenty of UV radiation from the sun, and there is the fact that UV-radiation tends to lower ORP of the water, which should make the water healthier. In short, there are a lot of common sense reasons to consider UV as part of your lighting solution. 

Hopefully the above helps as a guide to much about the discussion of light, and in general, you want to be aware of the fact that the typical old aquarium hoods are often under powered for serious plant growing. In the model above I've used such an old-line hood with a high quality fluorescent tube, and added some extra LED lighting, and, judging by the results sofar, this is a workable compromise. What remains to be seen if it is sufficient light once I start up my CO2.

The alternatives all involve throwing out the old hood, and using an open top and using really serious hi-tech lighting. Nowadays LEDs is pretty much the way to go.

• American Aquarium Products offers a great selection, here.
• Aquarium Plants also offers an impressive collection, here.
• And you can always find critiques on the various forums, and youtube.

A 10 Gallon tank

For my 10 Gallon tank I've used the existing hood as well, with a good quality bulb, and I've added another of the Marineland hidden LEDs, in this case a 17" model, and plants are thriving, so that combo seems to be effective.

Five Gallon nano-tank

For my five gallon tank I am running an 18W NemoLicht Aqua Fresh, at about 50% of capacity by day, and at the lowest setting by night. Sofar, this light has proven to be a good value, with its built-in controller, and a moonlight setting.

Conclusion

Obviously, you can search for yourself, but if you want to grow plants, I would advise you to study the advice from people who specialize on plants, for many of the popular, cheap lights, especially LEDs, will let you down if you want to grow serious plants. In most cases the complete tank setups will also be inadequate, unless you are really sure they come with light suitable for plant growing.

To be continued...