ditttohead
Water systems designer, R&D
Mesh size is not critical for softener applications, standard mesh will work, resin is very large compared to many other medias that use finer mesh screens. 18280 is for the 7000 when it has a 1.05" riser manifold (same as 3/4" PVC pipe size", 40697-02 is the top screen if you have the 32MM manifold. The majority of 7000 systems have the 32mm riser type.
Hope this helps,
Hope this helps,