Product review (1 stars): Sludge blocks draintube, floods basement
I bought this high priced Aprilaire  filter (2 actually) because the RPS replacement pad I had bought last year had jammed the drain with clay and dumped loads of water on the basement floor.

This replacement pad did exactly the same thing 2 weeks after installation. What happens is the clay impregnated on the metal pad comes loose and forms a gunk at the bottom which totally clogs up the drain tube. As a result you get a whole bunch of water on the floor and sludge into the condensate pump. This is a manufacturing defect which RPS admitted last year after I complained. And now the same thing is happening with the pad from Aprilaire.