I started a 20 gal CO2 injected (DIY) planted tank about 3 weeks ago and
I've been monitoring water chemistry and plant growth very carefully. There
are currently no fish in the tank, althought I will add some later to get it
cycling properly. The substrate is layered. 2:1 perlite:soil + a fine
gravel overlayer. All my plants are pearling beautifully and growing at
anticipated ridiculous rates. Good root structure developing too.

I have a couple of sword plants in there. One of them is still sending out
the "pre-maturity" broad leaves rather than the narrow sword leaves of later
plant life. I have noticed that on one of the newest leaves, the entire
leaf is healthy looking, but almost totally brown. There is not much green
to speak of in this leaf, but it is pearling like crazy and still growing.
Is this just a sign that this leaf has not developed completely?

On some of the other mature sword leaves, the vein structure is brownish.
Is this a result of high hardness or something else?

My water is also a bit on the acidic side, which seems odd, having such hard
water as I do. Coming out of the tap, dGH=25+, dKH=16+. I would have
thought high carbonate hardness would favor a slightly basic pH. Untrue?

I've exchanged a lot of tank water with RO water over the past few days in
an effort to reduce GH and KH to something reasonable. But with a soil
containing, mineral-rich underlayer, am I wasting my time adding RO water to
lower my hardness? Will GH rise over time by simple leaching from the
substrate?

Chemistry 01/17/05:
pH = 6.5
dGH=11
dKH=8
NH3/NH4+=0
NO2=0
NO3~0