Hi Virginia! There are two needles on the gauge. The black needle is the actual pressure on the outlet side of the filter. The orange/red needle is used to see what the pressure was when the cartridge was installed into the head. Before the cartridge is installed, turn the orange needle all the way down to zero. After you put the cartridge in, the black needle will push the orange needle to the setting of the newly installed cartridge. The orange needle will stay fixed and over time as the cartridge ages, the black needle will start to drop. This is how you can see the pressure drop over time and when you are due to replace it. Hope this helps!
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gauage
Hi Virginia! There are two needles on the gauge. The black needle is the actual pressure on the outlet side of the filter. The orange/red needle is used to see what the pressure was when the cartridge was installed into the head. Before the cartridge is installed, turn the orange needle all the way down to zero. After you put the cartridge in, the black needle will push the orange needle to the setting of the newly installed cartridge. The orange needle will stay fixed and over time as the cartridge ages, the black needle will start to drop. This is how you can see the pressure drop over time and when you are due to replace it. Hope this helps!