I think a 500micron pre-filter is adequate to keep out all fish eggs and newly hatched fry. The 50 micron will capture most all micro algae (phytoplankton) and all protozoans. Maybe esshup miss-typed? The 50 micron filtering dirty pond/stream water will develop rapid and serious clogging and will need frequent washing and cleaning with most any surface water except well water.

Last edited by Bill Cody; 09/26/21 07:08 PM.

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