In a planted aquarium what is more important, the spectrum of the light or the amount of watts?

Actually, despite what Gary suggests, the lumen output is as useless as the wattage. Lumen output is a measure that weighs the light output according to how huiman eyes perceive the light source. More important is the PAR (photosynthetically active radiation) which is a measure of light output weighed based on the uselfullness to photosynthetic organisms (such as plants). A light with a very yellow/green output will have a high lumen count but a low PAR. Most important to plants are red and blue light and it is important to choose a lamp that covers both of these areas rather than choose something that just looks bright. When comparing 2 lamps of the same type (such as fluorescent) the actual light emission will be basically the same (measured in energy output) but the one that produces more light in the spectrum you desire will be the best choice. So, if you want something that looks bright, a yellow spectrum will be best but if you want plant growth, red and blue output will be better.

Colour temperature (more accurately correlated colour temp. (CCT)) is absolutely useless to determine spectrum as they are largely arbitrary since true CT is based on black body radiation. Good quality lamps should have a spectral chart on the packaging and you can use this to determine if there is sufficient red and blue light in the lamps' output.

Neither the spectrum ("color temperature," which is what those "K" numbers stand for) nor the wattage is as important as the light output in lumens. Brighter light means more plant growth.

In very general terms, more watts means more lumens, but there is not a direct correlation, because some bulbs are much more efficient than others (i.e. able to put out a lot more light with the same number of watts.

So if the output in lumens is rated for the bulbs you are looking at, get the ones that produce more light.

If that information is not available, it's fairly safe to assume that a 20 watt compact fluorescent bulb produces a lot more light than a 10 watt bulb of the same kind. In fact, it probably produces more than twice as much light, because light bulbs become more efficient as their wattage increases.

In other words, between the two, I would go with the 20 watt bulbs. Be aware, however, that the 20 watt bulbs will cost twice as much to use as the 10 watt bulbs, since 20 watts is twice as much electricity as 10 watts.

The "K" numbers ("degrees Kelvin") are the "color temperature" of the lights. A lower K number is redder/yellower, and a higher K number is bluer. Natural sunlight is around 5000 K, but anything from around 4500 K to about 12,000 K is suitable for a freshwater planted tank. Some corals and marine invertebrates do better with a color temperature around 20,000 K, which will look quite blue to the human eye.

plants grow foliage on blue spectrum. They flower on red spectum. For plants in an aquarium, the more blue light the plant gets, the better. 10,000k is better than 6500k. 20 watts is better than 10 watts. So... 10,000k at 20 watt is far better than 6500k at 10 watt. Even in the event of flowering, 6500k contains very little red light.

a million. That relies upon on the vegetation you will shop. consumer-friendly to enhance vegetation do no longer care. universal gravel or sand will do. greater durable vegetation will choose an Iron wealthy substrate like Eco-finished. 2. Your decision. Gravel is gravel. For sand, you are able to no longer beet Tahitian Moon Sand, even nevertheless that is costly. I opted for the lots greater fee effective decision for my a hundred thirty gallon planted tank and used Pool filter out Sand. 3. lower back, that relies upon fullyyt on the vegetation you must maintain. consumer-friendly to enhance, low easy vegetation will do fantastic with a million-2 WPG. Medium and intense easy vegetation will choose greater. 4. no longer in the event that they are accomplished good. even nevertheless, in case you do no longer understand what you're doing, you will possibly desire to wind up with drastic PH swings that would desire to kill your fish. 5. particular. Hygrophilla will choose 2-3 watts minimum consistent with gallon. the rest might desire to be fantastic at a million.5-2 WPG. keep in mind that Anubias does not get planted interior the substrate, yet fairly related to wood or the like, and that the comparable is real for Java Fern, nevertheless this is partly planted if needed. additionally, Marimo Moss Balls, Crypts, and Amazon Swords. 6. in the previous. they might help with the cycle in case you get adequate. 7. no longer commonly, nevertheless they might in some situations nibble. you will no longer have any hassle in case you hold them ate up greens. (confirm which you have some driftwood on your setup in case you plan to maintain Bristlenose. that is taken under consideration mandatory to their weight loss software/digestion.) solid good fortune!

The spectrum of the light.