On brew day, before brewing, I clean the coolers, brew kettle, hoses, and fittings with Oxi Clean and a brush. A thorough rinse with the garden hose leaves no noticeable scent or residue on the equipment, and I think I am not using the "free" type. I've got to check now.
We have been using Oxi Clean in laundry for years, and no problems with the septic. Although, we switched from powdered laundry detergent to liquid since the powdered stuff has fillers that collect in the septic tank. Oxi Clean appears not to do that, perhaps because of the smaller amounts used.
As for carboys and primary fermentation buckets I use water and a brush only, then sanitize with Iodophor. I am worried about leaving soap residue inside, especially in the carboys where it is hard or impossible to scrub with a brush. I think that the plastic bristles of my dish brush (clean and dedicated to brewing only) will not scratch the primary buckets in a significant way. Anybody disagrees? That's what I have always done, and so far so good.
