SurTec 089 is a strong cleaning surfactant only for immersion, if you have agitation in your bath, also will cause the bubbles, It is normal and should be no problem if you have enough rinse bath. Consider about your production process as last time discussed. My suggestion for this issue.1. Decrease the SurTec 089 concentration, or even do not add, I think SurTec 133 have enough cleaning ability for your normal die case parts.2. One acid pickling tank before anodizing is also better to remove the residue surfactant.Hope it will be helpful for you