Blaster, you should not have any problem getting 1" wave in your 4f tank if you have a clear path straight across the tank. If your tank is full of rock, it is also hard to dial in the wave. Here is my recommendation.
1. Turn the white dialing knob counter clockwise till stop.
2. Slowly turn the dial clockwise. Give 1 min in between adjustment to observe the wave and a chance for your wavebox to build up the wave frequency.
remember, small adjustment at the time. If you make big adjustment you will never get the right frequency as the controller is very sensitive.
One misconception about the 6091 controller is the dialing knob. People thought if you are at the small end which mean your pump running minimum and if it is at the big end which mean you are getting larger wave and the pump at max power. That is not true because the pump always run at max power unless you are dial it down from the driver.
The white knob determine faster or slow pulse. when you are at faster pulsing, the interval also shorter (Best for shorter tank)
slower pulse come with longer interval (ideal for longer tank).
Every tank is different due to the rock work and flow inside of your tank. It is very hard to tell you where exactly the dial suppose to be. I have been helping many friend with 4f long tank and the lowest wave i can get is 1" and the max is between 1.5- 2".
Another thing you can do to help with dialing in your wavebox is turn off all the flow in your tank except the return. You can turn them back on after you are finish with the wavebox... If you need any help, feel free to ask or contact me... i'll be more than happy to help...