You may already know this, but I'll say it anyway. Your CP filter should have a rotating mount. If you rotate the filter 90 degrees you should see the effect increase or decrease. Just rotate the filter until you see the effect you are looking for. Also, not all filters are created equal. I am not sure which brand/model you are using, but some of the cheaper ones (like the off brand filters I started with) have a minimal effect. Also, these filters have different effects based on the angle of the sun. If the sun is directly in front of you the effect will be fairly little. The closer the sun is to 90 degree angle to you the stronger the effect will be.
Hope this helps.