you're welcome to disagree, carl...i'd rather be safe than sorry...most of my motivation to change the sand was based on how long the sand was in the filter given it was prior to my ownership. and, there seemed to be from what i've read here a solid benefit to using zeobrite over sand in terms of the filtration quality so if for no other reason, that made it worth it..honestly, if i hadn't bought the zeobrite, i likely would have just checked it each year and hoped for the best it also showed me that my prior tecnique for inspecting is not sufficient. gray stuff aside, moving my hand through the sand was not sufficient to feel the amount of clumping, in spite of using filter cleaner according to instructions all of 3 weeks ago. (clumps were breakable when vacuuming them out of the filter, but certainly not soft)

beyond that, i don't have enough experience with knowing what is sand going hard or not, and i don't think most people would.