Best Mechanical Fuel Pump

Fuel filter had some very small debris in it cleaned it out not a whole lot in there. Pulled the bowls floats are fine and this problem has happened on 2 different carbs BTW. Bowls on the carb had a few very very fine specs of "dirt" in it.

Is it normal to have anything at all in the bowls? I can;t imagine the filter is capable of getting it all. This stuff was very fine and not even able to CSI it to say anything other then dirt from the gas sation most likely.