Frequency tunning.

How do I know at what frequency my sub is tuned to?

Here's what I did:

I ran tests in my sub from 10Hz to 20Hz, because I think that my sub is tunned around those frequencies.

From 10Hz to 13Hz, there was a decent amount of air coming out of the port (like a fan with three settings in the middle position), and the driver's excursion was a lot.

From 14Hz to 17Hz, there was a lot of air coming out of the port (like a fan with three settings in the max postion), and the driver's excursion was a lot also.

From 18Hz to 20Hz, there was a decent amount of air coming out of the port (like a fan with three settings in the middle position) , and the driver's excursion was minimal.

From 25Hz and up, there was almost no air coming out of the port, and the drivers excursion was normal.