Originally Posted by MoneyMitch
so as far as kelven rating and intensity the powerglow will be my best bet for a planted with a run of the mill lighting setup? i mean it is brighter than the sun kelvin wise but i read another guys thread about plants turning brown and i caught a thread in there by you byron stateing that his lights may not have the intesisity that he needs. the guy said he had dual lifglow 2's, whioch you said are a great balanced light but on their own they dont have the intensity to kepe his plants healthy. im not too sure what plants exactly that i want but im thinkinbg of java ferns for sure something that will grow tall and bushy and then i want some really tall swords. maybe yall know more about what i am looking for or can point me in a direction so i can research a little more.
Kelvin is the degree of colour, nothing to do with brightness. Full spectrum (balanced) is basically the sun at mid-day and is 6500K (approx). So any tube with a K around 6500 is going to have the colour of mid-day sun. The lower the K number the more red (warmer) and the higher the K number the more blue (cool). But this is only the beginning. Two tubes with a K of 6700 can be very different in colour depending upon the emphasis the manufacturer gives to the colours. This is why I also look at the spectrum graph, to see which colurs are "highlighted" or strengthened, and by how much. See the graphs for Life-Glo and Power-Glo attached, and you'll see the significantly more blue of the latter. Both have a "spike" in the blue, but the PG is much thicker which means much more emphasis on this colour. The LG has roughly equal spikes in blue, red and green which is why it is so balanced (full spectrum).
The intensity or strength of the actual light has to do with lumens and lux. I have never bothered to delve into this too much because few manufacturers put this sort of information on their tubes, although i see the -Glo series is doing this. If you compare the lux/lumens of the regular Life-Glo tube to the T5 HO Life-Glo tube, you will see that the latter is 100 times more. This means it is brighter or more intense light. As I wrote elsewhere, I find it too intense and went back to regular tubes.
Intensity is partially linked to watts per gallon for regular tubes, and that is a fairly good way to determine it. It is not so accurate for the T5 HO because they are more intense, so fewer watts per gallon are required, just like the new compact fluorescent screw-in bulbs that at 13 watts equals the light of a 60 watt regular bulb. As long as you're thinking regular fluorescent tubes, watts per gallon is generally reliable, and I find 1-2 watts per gallon to be sufficient in basically low-tech setups like mine.
So, back to your powerglo, it is higher K which means more blue which is why it is a good light for plants. But it is also more intense. From the info it is rather more geared to marine setups that need/want a strong white/ble light to penetrate water for corals, etc. The Life-Glo has sufficent intensity, plus it is balanced to appear natural. However, in combination you might like the appearance; appearance is solely a matter of what you see, since either tube will be adequate for plants. The colours of the leaves and the fish will vary depending upon your choice of tubes.
Re the plants, Java Ferns are low light. Swords are generally speaking moderate (a few are high light). You've seen how well the swords (I have 7 different species in the present 90g and 6 species in the 115g) grow in my two Amazon tanks, with only 1 watt of full spectrum per gallon. Those tanks each have 1 Life-Glo and 1 similar tube for a bit more blue. The plants clearly have sufficient light. So the mix gives me the appearance i want, natural fish and plant colours with just a slight coolness from the emphasized blue.