Built-In DW Air-Gaps and other Anti-Siphon Devices
Most built-in DWs in the US originally required a drain air gap , a drain AG is the ONLY way to completely insure that dirty can-not possibility back up into your DW that is always installed lower than the sink and sinks drain line.
Many parts of the US did not require AGs so DW manufactures started building various types of built-in check valves into the DWs plumbing, these helped a lot, but if a tiny bit of glass or other object gets in the CV it will not function.
Having a high loop also helps a lot but of course dirty water can still siphon back through a HL.
Because of these improvements in DW design most places in the US have stopped requiring sink mounted AGs, here in the Washington area we no longer have to install them. We just loop the drain line as high as possible under the sink and secure it to the under side of the countertop and hope for the best. This type of installation would not pass muster in commercial installations etc however.
Hi Rich, in your case you can probably just get rid of the air gap or replace your AG, an AG should almost never clog so there is truly something wrong with your current AG if you are having to clean it on a regular basis, we still have thousand of customers with AGs and they generally do not even know they have one let alone know how to clean it.
John L.