HM Digital SM 1 In Line Single TDS Monitor, 0 9990 ppm Range, + 2% Readout Accuracy h160 Please Note: Additional heating units To maintain their well Please Note: Additional heating units may be required and discouraged from using in extraordinary setups (where warranty may be void) not limited to: Applications outside of standard aquarium use For maximum results add ReefBugs complete to a few ounces of aquarium water in a separate container and let sit for 20 30 minutes making sure to stir every ten minutes to ensure best hatch rate 6 centimeters Model Number SM 1 Number of Items 1 Part Number SM 1 Readout Accuracy + 2 percent Size Single TDS Monitor Specification Met Tds Range: 0 9990 Ppm (1 Ppm Resolution) UNSPSC Code 41110000 UPC 851905128852 The unit shuts off automatically after 10 minutes of non use