I tried some and wasn't impressed at all. Maybe I didn't use enough or let it dwell enough but it most certainly isn't as effective as Klein Wall
Soapy have you used that on extrutech? I seems I remember reading that it can make the plastic brittle.I use low fume Muratic acid from Home Depot. dilute it 3 to 5 parts with water. Brush or spray it on and let it dwell for a minute then a light scrub and rinse will usually clean about anything and it is much cheaper than anything else I have ever found.