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[APD] Re: lighting/myths

George pointed out an inherent problem with lighting regarding difference with each tank and it's unique set of variables.
While these parameters are unique  for each tank, the issue of more lighting is better, will grow plants healthier, is better for a tank etc,  redder plants ad nauesum..........can be solved relatively easily.
I find it somewhat disturbing that the main driving energy input , light, is seldom ever tested. George has a lux light meter, I have a nice Licore meter(1000$) and other goodies most never have nor will ever buy. The units (micromoles of photons/Einsteins/m^2/sec) are not meaningful to most aquarist but lux is a good unit for an aquarist, even if it is tougher relating that unit to research. Steve, I don't have any tanks right now to measure:) I use it the thing for work and research, not the hobby, but I'll get to it at some point. Work first.
People are often anal about ratios, nutrients, substrates and there is a an enormous amount of banter on the web on these topics, but folks seldom look closer at the two larger inputs, light and CO2. More CO2 is fine up to about 30ppm. Beyond this, not much increases in growth or efficency will be gained no matter how much light you add. See Bowes et al for references here. Bowes used 3 common fast growing submersed weeds to do his experiement. It is unlikely that slower growing plants will require more CO2.
Adding 25-30ppm CO2, nutrients etc will maximize the plant's ability to utilize all the light coming in.  
Since light IS the unknown in 99.9% of all tanks, it stands to reason that we should add enough CO2/nutrients to prevent limitation and then vary this parameter............much like when nutrient experiments are preformed.
The problem is that lighting is tougher to vary and measure. 
But back to the orginal issue Bryon mentioned:
"I want redder plants."
While low levels of NO3 will indeed do this, having high  light makes STABILTY of low leveles of Nitrogen that much more difficult. This is why many European tanks are able to have red color without high light.
You can do it with high light also, but you need to dose a lot and make sure you do not bottom out the NO3 levels.
You have much more wiggle room at lower lighting! 
This makes errors in dosing less critical, so less light will help maintain a more constant NO3 level. You can also get more out of your fish load, limit PO4 more(if you chose, which also will slow down NO3 uptake) and get more out of a substrate sources etc.
So an ideal set up in my view would be 2w/gal or so, Triton type color/output, lots of PO4/NO3/CO2/good deep sub/well pruned, good fish load etc.
Less light will give you a more stable NO3 level and a more stable tank in the long run.
It gives the plants time to maintain the coloration at a given level.
Speed(high lighting+ CO2/nutrients) is helpful for finding some things, but once you do, you need to slow it down and find the sweet spot. Some want the speed though(they say that, but after a few years, do they still?)
You can approach this from several angles, but less lighting makes the most sense(Cost, electric, heat, placement etc).
Adding 30ppm of CO2 does not cost much more and at low light, results in excellent growth with VERY little algae on the glass or anywhere. Plant growth and health is excellent without excess growth requiring so much pruning due to slower growth rates. Not a bad idea huh?  
That's something George has told folks on the APD for some years now. 
But heck, don't listen to us.......go ahead and add 5 w/gal of PC lighting with good relfectors to grow Gloss/Riccia/Eustralis/Cuba/ or the stem plant of the month.
We'll see how you feel 10 years from now:-)
Tom Barr
Tom Barr

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