Amazon has the API Fishcare 52Q API Tap Aquarium Water Conditioner (32 oz) for $8.99 - 5% off with Subscribe & Save (can cancel anytime) = $8.54 with free shipping on $35+ or with Prime (extra 15% off for 5+ subscribe and save orders). Chewy has it for $5.84 with Autoship discount on your first Autoship order, $8.99 for a one-time order.