GardenBanter.co.uk - View Single Post

05-08-2005, 07:33 PM

In article , says...
To the group:
I have just set up a new CO2 system in my tank. There were absolutely no
directions with the setup I ordered so I winged it and hope it works. Here
is what I have: a 5 lb. cylinder of CO2; a 200 reactor, a SMS 122 ph
controller, a bubble counter which is attached in line with the regulator.
My ph was 8.4 and is now at 7.6 and hopefully dropping to the recommended
setting of 7.0. My water KH is 8 degrees. I have no idea how much CO2 is
entering the tank and have no idea how it is measured. Do you count the
total amount of bubbles in the bubble counter per minute? I have NO idea.

I also have the CO2 solenoid plugged into a timer which shuts off the
solenoid at about 8:00 p.m. and then turns on again at 7:00 a.m. Is that
right how it is hooked up and is the timer set about right? Plants are
arriving tomorrow.

Can the group please advise whether or not I am on the right track and have
hooked this system up correctly?

Dan

Hi Dan,

Several things to note here. First, you say that you have an SMS 122 controller,
but also that your solenoid is plugged into a timer. If the controller is to be
able to control the solenoid, then you need to plug the solenoid into the
controlled receptacle on the SMS 122. It will control pH by opensing and closing
the CO2 solenoid valve when necessary. There is no need to shut off the solenoid
at night when you have a pH controller, and for most tanks no need even if you
don't have a pH controller. (Because most of the CO2 is lost to the atmosphere,
which is constant day and night.)

But before you do that you should set a reasonable CO2 flow rate using the
regulator and needle valve. You half-filled the bubble counter with water ? Good.
Now close the needle valve and screw in the large knob on the pressure regulator
until you get some indication on the low pressure gauge. You want the needle to
come off the pin, but you do not need too much pressure. Try to adjust for the
first or second tick mark. Five or 10 PSI is plenty. If you overshoot you have to
open the needle valve to release pressure. This pressure setting will drift
slightly over 2-3 days, so check it and adjust maybe twice a day for this initial
period. Then it will stay by itself. Now adjust the needle valve to set the
_maximum_ flow into the reactor. Here is where you use your bubble counter as a
flow meter. The needle valve is a bit touchy. Once you get close to the correct
adjustment, your fine tuning will be maybe 1/16 of a turn. Set it for about 2-3
bubbles per second. For most tanks up to 100G or so, this would represent plenty
of CO2 if your reactor is efficient. It will be more than is necessary for a
smaller tank that does not have a lot of surface currents and rippling.

Now you can move the solenoid plug to the SMS122 and let it turn off the CO2 when
the pH drops to your setpoint. Don't forget to check and reset the regulator
pressure setting for the first few days, or until it settles in to maintain your
pressure setting. If the bubble rate (with solenoid on) falls off, only adjust it
after the pressure is where you want it. The usual drift of both regulator and
needle valve causes the CO2 to fall off during the first days of use. Maybe you
adjust it a few times each day for the first day or two, then once a day for the
next two days, then just check it once a day until you are confident that it is
holding.

The pH probe itself has some long term maintenance requirements, and a limited
lifetime. You should probably search around the web for specific info on it and
the calibration procedure if there is one.

As far as ph=7 with KH=8, that would represent a fairly high level of CO2 and
probably more than you want. Maybe better to use a setpoint of 7.3 for right now
until everything is stable and you are confident in the gear and your ability to
monitor it.

-Geo.