Paddle tester, total aerobic bacteria, total coliforms, 10 piecesPaddle testers allow fast, easy screening of water samples, solid surfaces, and nonviscous liquids where unsanitary conditions may exist.Hach Paddle Testers allow fast, easy screening of water samples, solid surfaces, and nonviscous liquids where unsanitary conditions may exist. The paddle is a double-sided slide attached to the vial cap. Each side of the slide is used to perform a separate test. The slide has a molded-in grid for easy colony counting without opening the optically clear, leakproof vial. Paddle Tester, Total Aerobic Bacteria/Total Coliforms (Tryptic Soy Agar/Violet Red Bile Agar), pk/10.