I have to disagree with the poster who suggested the regulator does not let you adjust the output pressure. that is what the screwdriver slot on the front does. Try it for yourself, with the needle valve disconnected from tubing and opened up wide. The left gage should change from the "6" setting. However, that setting is for 6 LPM - liters per minute - if I have interpreted the dial correctly. In the USA they are usually measured in PSI - pounds per square inch. But note that even 1 liter per minute is a lot of very small bubbles in 60 seconds!!! I recommend you remove the pH meter from the equation initially to make sure it is set correctly. Just plug the solenoid plug into a wall socket - to cause the solenoid to the on all the time. Then adjust the needle valve to the number of bubbles per second that you want. Eventually you will not need to be real precise on this - as do those of us who do not need a solenoid - as when your co2 is sufficient, your co2 gas will shut off. For now I suggest you set it for about 2 bubbles per second. Once you have that working, then setup the pH meter again. At this point, when the pH meter turns on again, you should only have the 2 bubbles per second output. Good luck. For lots more info on pressurized co2 systems, take a look at my web site: http://members.cox.net/tulsaalstons/AquaticPlants.htm#High%20Pressure%20CO2 Bob Alston 918.494.4913 BobAlston9@AOL.com http://members.cox.net/tulsaalstons/ --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.752 / Virus Database: 503 - Release Date: 9/3/2004 _______________________________________________ AGA-Member mailing list AGA-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/aga-member