DO NOT USE CO2 - This is no troll - I've tried for one year now and it
makes black hair algae grow like mad - save yourself money and
trouble. Just don't do it.



Depends on your lighting. CO2 isn't necessary for a low-light tank. But for a
high-light tank (over 3 wpg), it's essential. That much light without CO2 will
not cause algae problems, it may also lead to pH swings severe enough to kill
your fish.

Though studies have shown that CO2 helps moderate-light tanks, possibly even
more than high-light tanks, IME, it's not worth it. The plants grow fine
without it, the pH is stable, and all CO2 gets you more time pruning. So if
you have 2 wpg or less over your tank, then yes, your life may be easier
without CO2.



Leigh

http://www.fortunecity.com/lavender/halloween/881/