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Re: co2 and aeration

>I have a 100 gallon gal plant tank that I have been running for
>several weeks. I use most of the Dupla method and their equipment and
>supplements. I presently use a Neptune controller for the co2. I have
>one problem my ph has been dropping to 6.50 during the night and
>slowly rises to 6.80 after the metal halides come on. The set point
>for the co2 is on at 6.80 and off at 6.75 1 have been considering
>adding another timer to turn a air pump on when the ph drops to 6.60
>and to turn off when the ph rises to 6.70. I believe that the aeration
>will only be on when the lights are off during the period that the
>plants also use oxygen. please let me know if this is a good idea.
I have a 55 gal tank on which I use a prefilter, a filter, a "Quiet One"
pump and a post filter/reactor(a hang on the back filter made from an 18"
piece of 3" PVC.)  I tapped into the water line between the pump and the
filter with an air line.  I have a ball valve on each end of the filter
system so I can adjust the pressure at this point to be negative with
respect to air.  I built two bubble counters; one for CO2 and one for air.
I adjust the air to introduce about the same amount as the CO2.  The pump
impeller breaks the air/CO2 into tiny bubbles aiding absorbtion.  My tank
runs a very stable pH of 7 both night and day.  I have not observed any
variations from changes in oxygen levels.  The main differences between the
setup you described and mine is I use the water pump to get a negative
pressure so I do not need an air pump and I inject both CO2 and air at the
same place; I don't see why your method shouldn't work just as well.

k5vkq at ix_netcom.com