humic chelation,biogen.decalc.,red plants,blue light

1.)	I've been thinking that since both peat moss and Zaire bogwood
leach humic acids, they should both have some ability to chelate the trace
elements my plants need.  If this is so, has anyone done any studies to
measure this ability?  
	I also hope to use the peat and wood to help soften and acidify my
water, which brings me to another problem: I have a 40 gal. set up with
two 20 watt full spectrum flourescents, (I believe they're around 5000K) a
13watt compact flourescent, also rated at 5000K, and a 9watt compact at
7100K.  The tank is fairly shallow, with the top of the gravel averaging
around 12" from the surface, 14" from the lights.  The substrate is fine
gravel, laterite, Tetra Crypto?. and is about 3.5" deep.  I have a corner
of Green and Red Wendtii, a different corner with Anubias nana, the back
has a nic healthy bunch of Java moss growing around my heater (a little
secret for Java moss success;-), two small (for now) Red Mellon Swords
(Osiris?), and an interesting sword called a Tropican.  (It too can get
some nice, deep red leaves, but I wonder whether anyone can tell me more
about this plant like its scientific name, etc.).  I also have an almost
uncontrollable mat of duckweed on the surface, which I have to thin
constantly. I have a power head hooked up to a spnge filter in one corner,
and a tetra billi filter (kept bubbling slowly) in the other.  There are
currently no fish in the tank, though I plan to move a nice school of
trifasciatus pencils and my prize Corydoras Sterbais! (Perhaps _the_ most
beautiful Cory out there IMHO) into the tank once I get the following
problem solved:

2.)	My tank has this annoying habit of rising pH during the day,
sinking at night.  I am assuming this fluctuation is caused by bicarbonate
assimilation aka biogenic decalcification, since I have nothing else in
the tank that would cause this to occur. ie no shells or reactive rocks in
the tank, and naturally occuring low alkalinity and hardness. I suspect
that the duckweed is the culprit, but I'd like to hear other opinions on
which of my other plants could be guilty.  What are my options (besides
CO2 injection, if there are any), to stop this pH change? I don't want to
put my fish in, since teh fluctuation is drastic enough to do them serious
harm! e.g. would peat in my tank be able to neutralize the effects?
3.) Has anyone done any studies to investigate the idea that red plants
benefit from more short wave-length blue light? Mine _seem_ to be, but I
haven't exactly done a controlled experiment.

4.) I've been thinking of switching to T-8s, but can find neither 2' nor
    3' bulbs over 4100K.  If I mixed these with two 9w cf 7100k, would
    this be any good? Better than my current set-up?

			Sorry for the long post,
				The Drew-ed

When an eel bites your leg,
and the pain makes you beg,
that's a moray :-(