Didn't need to calibrate as mine came out just perfect, seems to come out of the box. Tested with a known volume of water for PH and TDS. I've been using it in aquarium water for about a month now and so far both have worked with no problems. The PH is always between 7.1 and 7.25, which is consistent with where he used the API test kit or test strips. TDS rises slowly for a week until water change, then falls slightly and repeats. definitely worth the money.
Razorri Comodo Ceramic Fermentation Crock - 2L Traditional Water-Sealed Jar With Glazed Weights - Perfect For Kombucha, Sauerkraut, Kimchi, Pickles (Tangerine Tango)
23 Review
24-Inch Musical Christmas Tree With Charlie Brown & Linus Blanket - ProductWorks
37 Review
YEAHBEER 3.2FT Felt Christmas Tree For Kids Wall With 30 Detachable DIY Ornaments - Xmas Gift And Door Hanging Decoration For New Year Celebrations
38 Review
WINKINE Acrylic Riser Display Shelf: Versatile 4-tier Organizer for Perfumes, Amiibo and Funko POP Figures
28 Review
AmazonBasics Silicone Baking Mat Sheet
48 Review
300PCS Pre-Cut Unbleached Parchment Paper Sheets - Perfect For Baking, Grilling, Air Fryer & Steaming!
36 Review
GOBAM Wood Rolling Pin: The Perfect Dough Roller For Baking Cookies, Pie, Pizza & More - 13 X 1.38 Inches
35 Review
SMARTAKE Non-Stick Parchment Paper Roll, 13 In X 164 Ft (177 Sq. Ft) For Baking, Cooking, Air Fryer, Steamer, Kitchen, Cookies, Bread, And More - White Baking Pan Liner
41 Review