In most cases, no. Ritchie valves are free flowing and most small particles will pass through the valve and end up in the bottom of the trough. When the unit is cleaned, these particles go out the drain. If the particles are large and causing the valve to clog or stay open, the answer is yes. A screen, such as an agricultural sprayer uses, may be more desirable than a filter. A filter will plug up sooner than a screen. A screen will pass particles that will go through the valve with no problem, whereas the filter will trap them. It is important on new installations to flush the lines of all debris, such as PVC shavings, before hooking up the fountain.