Our problem is mainly pet hair in the washer drain line. I tested some of the residual fiber that got caught in our dryer filter. I used a sample with chlorine bleach in a jar, and a similar sample with concentrated sodium hydroxide solution I made myself in a separate jar. In about 30 minutes the animal hair had dissolved completely in the bleach. The synthetic fibers were virtually unaffected. I let the sodium hydroxide experiment run for 24 hours or so, and the animal fibers were still quite intact as were the synthetics. Here's the deal: bleach works for protein (like hair). Sodium hydroxide (lye) works for fat. In fact, sodium hydroxide + fat = soap. As far as mixing the two goes, I'd say don't. Liquid Plumbr contains sodium hypochlorite (bleach), sodium hydroxide (lye), and sodium silicate (which is simply denser than water and helps carry the active ingredients through the line. But knowing there's bleach mixed with sodium hydroxide in Liquid Plumbr says absolutely nothing about the relative concentration of the two chemicals. Chlorine gas liberated from bleach by doing something stupid can kill you, blind you, burn you. But we use about 1/2 gal of bleach in our washer drain line after washing blankets covered with animal hair. We can leave it in overnight if we forget, and no harm done. Old cast iron drain line mated to 4" PVC.