Re: low KH and DIY CO2 adaptation

>	I have two planted 55 gal (All Glass 48"x12"x12") tanks.  They each
>have a small school of ottos and 6-8 juvenile angles in them.  My tap
>water is very soft, has a Kh of less than 2, and Ph of about 6.8-7.0.  The
>tanks are both lit with 80W of flourescent light (1 triton, 1 vita-light).
>I use duplaplant and the dupla 24 drops.  The growth is ok and you can
>normally see O2 bubbles coming from the hygrophilas and echinodorus most
>of the day.  I have been using DIY CO2, but it only lasts 5-7 days before
>it needs to be changed.  Also, due to my soft water and its low Kh, I've
>had to use baking soda to increase the Kh to minimize Ph fluctuation. 
>Okay, here are my questions:
>	o my light is only moderate, is the CO2 at these levels even
>helping things enough to justify its use and the instability of Ph it's
>causing at this time?
>	o I can't afford a "real" CO2 setup, if I continue using DIY what
>can I do to eliminate Ph fluctuations and stress to my fish and plants?
>any hints or ideas would be greatly appreciated.

I have very similar conditions to yours. The DIY CO2 is well worth your
while. Try increasing the sugar or reducing the amount of yeast in your
batches. One bottle lasts me 17 to 20 days and provides for the needs of
the plants in the 180 gallon. To maintain stability start a new batch
three days before the old is expected to expire or slow down. Are you
adding baking soda to the batch? I don't know if it is necessary, but
I also add 3 drops of AMQUEL to the bottle.