the ph is low because of the buffering from the co2.. Stop the co2
injection and you will see your ph skyrocket. You can tell how much co2 you
have by using a co2 chart by just measuring your ph and kh. As long as you
have no other buffers other than bicarbonate this would put your co2 at
about 76ppm. Not at all good for fish. It seems most people shoot for
around 30ppm of co2 in planted tanks.

here is a good co2 chart
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm


And you definately need more nitrates as others have suggested. I am not
sure how much it will help, but it is necessary.
--

Margolis
http://web.archive.org/web/200302152...qs/AGQ2FAQ.htm
http://www.unrealtower.org/faq