K temperature Question

Yes, I've also read elsewhere that the growth of the plant, regarding short and wide or tall and slender, can be affected by K rating, insufficient red going one way and insufficient blue going the other. Ragarding wattage, there are several plants that will "burn" under too much light which must be taken into account as well. Regardless of the color spectrum, as long as there is enough light any plant will grow, but again, caution is needed to avoid burning some plants and even those that don't burn will grow better under a good ballance of red and blue light due to better usage of the availible CO2 in the water. JMO based on everything I've read.

?: When discussing W/gallon, I assume that this is based on standard fluorescent lights, correct? So how does one calculate the variation when using power compacts or VHO, ect, as compared to the output of actual light from a standard floursecent since these options provide significantly more actual light per watt?
 
I think we are ultimately saying the same thing. PAR is the final answer. Different lamps will provide different amounts of PAR.

Given the likelyhood that kelvin ratings on aquarium lamps are widely inaccurate, I'm saying that wattage(or lumens) will be a far better estimating indicator of PAR on commercial packaging than "kelvin". Bulbs differ, all 6700k bulbs are not equal.

Given that the hobby is swinging towards PAR, it would be nice if manufacturers would includ that data on the package along with or instead of lumens.

That's my hypothesis, which does indeed require some testing.
 
This is what I don't understand; Why are PAR and Kelvin being discussed at the same time? They are so incredibly different, it's very confusing.

PAR is simply a relative measure like the Lumen. The Lumen is based on how well your eye sees light, and PAR is based on how well plants use light across the spectrum. The lumen or PAR rating on a bulb is an indication of the "total" light.

Kelvin is a measure related to the apparent color of a piece of pure carbon heated to the specified degrees kelvin. Heat it to 2700k, and the light is roughly the colour of your average yellow CFL. Heat it to 6500k, and you get colour similar to a "daylight" cfl. Kelvin is a relative apparent colour measure, it does not indicate distribution across the spectrum and ONLY indicates the temperature you would have to heat a piece of carbon to in order to most closely immitate that light colour.

The Kelvin rating is not likely to affect the growth of your plant in terms of absolute mass. It will, however, effect the "behavior" of the growth of your plant, and can effect processes like flowering or fruiting.

PAR is simply a boiled-down version of Watts, they each are a measure of energy. The wattage of a bulb is the amount of energy it will use-up, the PAR is the amount of energy produced by that bulb as it relates to how well a plant can absorb it.

Simply put, Kelvin will effect the *look* of your tank and plants, but not their health.
 
What looks good to the eye is a personal preference. I tend to gravitate towards full spectrum daylight bulbs with a high CRI rating.
 
....wow.... So "watts per gallon" is pretty much useless unless you are using T12 bulbs I guess. Certainly complicates matters some.
 
Mindcrime121 said:
....wow.... So "watts per gallon" is pretty much useless unless you are using T12 bulbs I guess. Certainly complicates matters some.
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Eye of the beholder. To the advanced aquarist, watts per gallon is useless. However, it is a decent guideline to start with.

PAR data isn't readily available, so therefore it's useful to consider watts or lumens. Personally, I consider the debate between watts and lumens to be futile....each is inaccurate in it's own way.

Watts per gallon "rule" has served many well, and is easily understood, so, like I said, as a starting point, it is a great guideline. For tanks 20g to 80g, nobody ever failed(at the lighting, at least) by following the watts per gallon guideline.
 
Understandable if dealing with T12 bulbs, but then if you consider that there are "low light" plants which burn under too much light and you throw the "right " amount of wattage over them while using T5 bulbs, and calculate the lumens per inch, then you may find that you are puting a whole LOT more light on those plants than you think you are. That is where I'm getting thrown yb the "watts per gallon" rule when considering the difference in light output between T5 and T12 as an example, much less halogen, T5HO, and so on... Following the watts per gallon "rule" may ensure that you are not short of light, but it seems t me that it could lead you to put WAY more over the tank than you want for the types of plants you are growing.
 
There are no plants that burn under too much light, even java ferns will grow like tank busters under 8wpg. The only reason why we shouldn't use excessive lighting is because the growth rate would be too much and would put too much demand on nutrients, become deficient in some and algae will quickly take over.

For our purposes, the K rating is only important in helping us determine the light color we want. Ignore the recommendations that state you should use something in a specific K rating to improve plant growth, they are simply wrong.

The wpg rule for all its faults is simple to follow and quite effective if you think in the general term. Yes, it's designed for standard tanks using T12 fluorescent. That just means you need to aim a little lower if using more efficient lighting.
 
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