20 Gallon Stand & Long

My wife and I are new to the list, but have a couple of questions
regarding CO2. Her tank is a 20 gal long with many, many plants--
sorry, I can only identify two Amazonian Swords--along with 3
swordtail wags and a blue crayfish. Filtration is the Millenium
2000, which seems to be doing a splendid job, but if I understand
correctly some of what's been said here, I'll have to use laterite
balls or find a way to replace the Millenium cartridge which contains
charcol, to get iron in the water. We also use an Aquaclear powerhead
drawing through a sponge and with a diy CO2 infuser connected
to the output. We get a steady--every 5 seconds or so--output of
fine bubbles from the powerhead this way. Because the tank is
so heavily planted, I turn on a Tetra-Luft air pump connected to
a wooden air stone set to go on as soon as the lights go off so
as not to risk suffocating any fish. pH has run 7.7 or .8 even with
CO2 and no airstone. But the tapwater here will buffer battery
acid. Nitrites still show up as the tank is not quite a month old,
but we used water and filter sponges and gravel from our established
20 to start this one, and 10% water changes every other day 
during which I vacuum lightly with a Fluval 103 and let it run
for an hour or so because its center cup is filled with peat.
This keep any nitrites barely detectable while the nitrates rise slowly.

Questions are, am I right to worry about fish and inverts needing 
more air with the light off (24" 20 watt Triton bulb), is carbon
my enemy in a mainly planted tank, and does the tank's configuration
(ie, top of gravel bed is only 10" from light source) still 
mandate additional lighting--that is do I still need, say a 2 or 3 watt
per gallon ratio to maintain growth?

  Interestingly, our 20 standard, which has a 15 watt Triton along
with diy CO2, has four plants of its own, though it's mainly a
fish tank. These plants, including on Amazonian Sword, seem to be
doing better than those in the 20 long, even though I keep two air
stones running all the time and this probably negates most of the
CO2 (also dispersed via powerhead, a Penguin 1140). But it seems
to be working--pH runs about 7.7 or .8, and nitrates stay at 30-40
with 10% water changes every 5 days (main filter is Aquaclear 200
with two sponges and alternating carbon and peat bags on top). I
suppose these plants benefit from the higher nitrates of an established

  I guess I'm wondering if anyone has any impressions or suggestions
about either setup.  


Andy & Lisa Katz