Releasing spa filter pressure

[calgecko]

I have an old Southwest Industries portable spa with an attached filter. I am trying to figure out how to release the pressure from it. In the attached photo, there is a gray tab at about 7 o'clock (in the photo) on the filter that jiggles around a bit. Do I pull on this or push it out to release the pressure, or is there something else that releases the pressure?
[attachment=0:3dew3bve]filter.JPG[/attachment:3dew3bve]

The label on the filter reads "Caution: Contents under pressure. Turn off pump and open air relief valve before removing filter top."

 

[calgecko]

Ok, I figured it out. To the right of the label is a small nut that releases the pressure...that was easy.
Also, it's not the filter (which is weird because it calls it a filter on the sticker, or maybe I am missing a filter element inside it), I think it is some kind of pressure chamber to allow the jets to squirt out air, maybe someone can enlighten us on that.
The grey tab fits into a slot in the bottom of the big ring around the system, lift it up and unscrew the ring. Once the ring is removed (hope you've eaten your wheaties for that one), you can pull up on the handle. The handle is basically a big plug with an o-ring. Turning the plug doesn't help because there's no screw thread. Inside is basically empty, but at the bottom is a pipe with what looks like a spring-action valve.