Q. Which side of your polishing pad should the water go through first?
A. If both sides of the felt pad are soft to the touch then water will flow equally well through either side therefore it does not matter which side goes up. However, if one side of the felt pad feels rough to the touch it has been heat treated to keep fibers from migrating or pilling after cleaning. When using this felt pad it is best for the water to flow through the soft felt side first.
Q. Does the 50 or 100 micron polishing pad trap the finer stuff from my aquarium water?
A. The smaller the number of microns, the smaller the holes in the polishing pad. In this case, the 50 micron will trap much finer particles than the 100 micron.