While I was out, I stopped at the farm-supply store and picked up two bags of medium-grit filter sand. Or should I say "struggled to pick up the sand." Did you know that a cubic foot (28.3 liters) of quartz sand weighs 100 pounds (45 kilos)? And because it's loose material, the bag is "dead weight": everything shifts around, and there is no internal support. Fortunately, I was able to get them out of the car trunk (boot for those of you in the U.K.) without wrecking my back. I bought two bags so I won't have to go back for a while.
I spent the rest of the day mixing up a huge stockpile of carnivorous plant soil so I can do some serious repotting this week.