My neighbor Greg walked into my backyard on Friday evening for our weekly cornhole series, looked down into the deep end of my pool, and asked how much I pay a service company to get the water looking like liquid glass. While lining up a push shot on the 3/4-inch birch board, I told him the truth: I don’t let pool companies near my yard, and I haven’t stepped foot inside a retail pool store for “free water testing” in four years.

If you walk into a pool store after a heavy Maryland thunderstorm, their computer will tell you your Total Alkalinity is low and hand you a 10-pound plastic tub of “Alkalinity Increaser” for $26.99. Flip that tub over and squint at the fine print on the bottom label. Active Ingredient: 100% Sodium Bicarbonate. That isn’t proprietary pool magic—it is literally baking soda.

Instead of paying the pool-store tax, walk into the warehouse club or grocery aisle and grab a 13.5-pound bag of Arm & Hammer for nine bucks. Pair that with liquid chlorine, a $1 mesh skimmer sock, and a real FAS-DPD drop-test kit (throw the guessing-game paper dip strips in the trash), and you can read the mint year on a quarter in the deep end all summer. I explained this to Greg right before sinking a four-bagger to take the first game 21–14.