Clocking in at only an hour, Deeper Than Y is a lithe documentary about the trials and rewards of reaching advanced age, as well as a gentle rebuke to a society that has little time for the elderly. The mostly gray-haired members of a water exercise class at the Vanderbilt YMCA in midtown share their stories and reflect on how it feels to be slowing down at a time when the pace of life is accelerating. The interviews are lively, though not all documentary subjects are created equal, as becomes apparent when Gerty Agoston is introduced. A Hungarian American pulp novelist whose apartment is adorned with pictures of Nixon and Reagan, Agoston published her first book, My Bed Is Not for Sleeping, in 1968, followed by the more provocatively titled My Husband Is a Magnificent Whore. The other stars include Mel and Andrew, a gay couple who recently celebrated their 36th anniversary, and Frannie, a nonagenarian who talks about finding true love at 66 and continuing to flirt into her 10th decade. The subjects seem happy to have made it so far, but they lament the physical pain of aging; says 86-year-old Ira, with a twinkle in his eye, “How does it feel getting old? Rotten.”