I've been running biopellets for a few years. tried various brands. Dr. Tim's caused massive sludge build up in reactor and i gave up with that. now running All-In-One (gfo coated). these do not clog reactor but the effluent residue needs to be dealt with. I used to run effluent piped direct to skimmer intake, now i run biopellet effluent into my 100 micron socks. I also suggest trying different brands of pellets. your redslime problems are either due to other husbandry issues, flow issues, or perhaps biologic (nutrient) imbalance that may have some connection to your biopellet setup.