That is the question. The sock method is kind of a pain for me as I believe I have a small leak in the lines somewhere, so I have to add CYA more often than I would like. If I could just get it into the sand filter would it not dissolve there? My thoughts are to pour it in slowly into the skimmer and let it flow through the pump to the top of the sand filter and let it dissolve there. Anything damaging to the pool or wasteful to do it this way? CYA seams to be a tame acid.