C02 Regulator problem

[Markster]

I have a Milwaukee MA957 C02 regulator that I can't seem to keep a steady bubble count. I am running it with a 10lb tank and SMS122 pH controller. I just refilled the tank from Natwells so I know there is C02 in the tank. I set the regulator adjustment and then use the fine needle to set the bubble rate. I leave it alone for 5 mintues and the bubbles practically stops. I have tried everything and nothing seems to work. Could the solenoid be bad?

[RobertG]

Mark Bypass the selonoid & see what happens. You do have a controler, how is the ph being monitored? Effluent or tank ph? Have you calibrated the controler? What is your target ph? Sounds like the controler is turning the co2 off. This is good. If it is hitting the target ph. Very well could be a bad selonoid.

[Markster]

How would I bypass the seleniod? ph being monitored by the electrode in the sump. Just calibrated the controller yesterday. Target ph is 7.5 and the alarm red button is flashing, which lets the CO2 flow. Controller reads 8.0 ph at the moment.

[VGB]

Perhaps a long shot but do you use a check valve on the CO2 imput to the reactor?
When I have had trouble holding a steady bubble count, my check valve has always been at fault.
Once after a recharge I installed it backwards. Also since its brass, I try to keep it clean and the spring slighty lubed.

A stuck/stiff check valve will lead to problems such as this if you employ one.

[Markster]

No, I don't use a check valve. I called Milwaukee Instruments and they said the problem lies in the needle valve. They suggest opening it all the way and then just using the regulator knob to obtain the desired bubble count. The second gauge is not required and they said cover it will a bag as the pressure needed is so low that it doesn't mean anything; thus the bubble counter is included.