Re: Pressurized CO2
I suggest first raising the regulated pressure to about 20 psi instead of 9. Then crack the needle valve until you get around one bubble per second. Watch it off and on until you know it remains constant. Then try sutting off the solenoid, waiting a minute or so and opening it again to see if the bubble rate resumes at the same setting. If all of that is ok, start checking the fish to see if they act normal and don't cluster at the top of the tank, lose color, or otherwise look distressed. Then raise the bubble rate a little each day until you finally see some distress in the fish - don't ever raise it and leave it unwatched for a day! When you see some distress, back off a bit on the bubble rate and make sure the fish act normal again. That is the highest, and therefore the best bubble rate for that tank, with that method of diffusing. Remember the bubble rate, remember the pH and KH and use those numbers to control the CO2 to a constant rate. Let the solenoid shut off the CO2 at night to give the fish a break, and turn it back on for the lighted period.
Rather than worry about what the tables say your ppm of CO2 is now, just treat that number as a dimensionless indication of what you will now use as your CO2 flow rate. So, if your KH changes, you can still go back to the same CO2 rate using the tables. You just wont know what that true rate is.