When I change the water which is now every 3 to 4 days due to being so late in flowering and a small res, I have the same slime like shit your talking about. I believe this is the Heisenberg tea, (beneficial bacteria) I run. I do wipe down the hoses and pump etc... inside my res, but I DO NOT RUN ANY h202 as it kills all bacteria good or bad. If your roots are white, or just a bit stained from the nutes I would not run h2o2 unless you are buying some of the new products for root maintenance that are h202 resistant.