The information sheet on the GEA heat exchanger says "A water strainer MUST be installed in the water inlet circuit (16-20 mesh minimum, 20-40 meshrecommended) I looked at a Watts: 777SI, S777SI | Wye Strainer-Standard Screen: #20 mesh, 304 stainless steel. Are these the fittings I would want? These specs are minimum for GEA but I did not find ones with finer mesh. Does brass or cast iron matter? Cast is obviously less money.