This may happen when the needle valve adjustment directions are not followed. Read page 13 of the Clear O3 Instruction Manual on how to set flow meter.
To adjust close the needle valve on the flow meter and with the pump running open it just a little. Let the unit run for several days that way and then if it has not dropped tap with your finger on the sight glass to knock the ball.   If the ball stays stuck and will not drop replace the flow meter.