First aluminum welds with PT200DX

These are some of my first aluminum welds.I have just been playing around with AC balance and AC freq. but was told these have alot of etching around them.How can you reduce the etching or is it really hurting anything with the weld quality.
Attachment 525

Turn your balance all the way to the left. That will be your best setting for this. Use a little more heat and more speed. Set your flow meter to about 5-7 lpm