Thank you for your email Carl! All Honda gas powered pumps include a suction strainer similar to THIS that are sized based on the allowable solid handling size that the given pump can handle. This strainer gets attached onto to the suction hose end that is in the pond, creek or any other water source you may be utilizing. These strainers will have the same size threaded NPT connection as the suction and discharge ports on the pump you purchase.
Since this strainer is included, there is really no need to include any other inline filter when using this pump.
If you have any other questions, please let me know.