Do I Need CO2???

Hi,  I do not inject CO2.  I wanted to try the yeast-sugar method, but... I
did some water tests over the weekend before I made my weekly water change.
I want to know do I really need CO2?  According to my test results and the
chart in "The Optimum Aquarium"  I do not need it.  I think I do not need
it. <G>  Here is what I got.  Water temperature was 84.  It has been hot and
if I do not have to use the air conditioner I won't. My pH is 6.0 in the
tank.  From the tap 7.0 is the pH. Using a Tetra test kit I got a reading of
1dh of KH and 6dh of GH.  I got the same readings from the tank and straight
tap water when testing for hardness.  According to the chart in "The Optimum
Aquarium" which determines CO2 levels according to pH and KH readings I have
a CO2 level of 30mg/l.  Is this chart accurate?  Do I have CO2 in the amount
of 30mg/l?  The chart says I have too much CO2.  I then used the Tetra CO2
test kit I have and got a reading of 2, 5, - 15 mg/l.  For those that are
not familar with this kit, that is all the higher it will go.  It only tells
you if you have enough, or not enough CO2.  It does not give an exact
reading. I do regular water changes once a week.  One quarter of the water
in removed and I lightly hover my Python water changer over the gravel in
the places I can.  For the first time I bought an alkalinity test kit and
got a reading of 10 for alkalinity/buffering capacity.  To get a more
precise idea if my water chemisty I requested a water report for my local
water.  I should have got it Monday.  I hope it will get here today and my
readings will match their readings.  Tetras O2 test kit gave me a reading of
8 mg/l.  Nitrate was 25 mg/l.  I made the same tests before and after the
water change and got the same readings each time.  I have 120 watts over my
tank which is 55 gallons.  Hygrophila I know isn't hard to grow.  What can
you tell me when I say my Hygrophila has as red color in the top leaves and
veins and the top leaves are reaching up?  They want more light, have too
much light, or just enough? The lower leaves are green.  


"There are always exceptions to the rules"