Nutrafin General Hardness (GH) Reagent Refill for Aquarium for Aquarium， 10ml</br></br><div style="text-align:left"><b>[Product Information]</b><br><ul><li>General hardness (gh) reagent refill for use with nutrafin carbonate and general hardness test kit</li><li>Testing for general hardness (gh) should be done to determine if the levels of calcium and magnesium are optimal for specific species of fish</li><li>Measures 1-inch length by 1-inch width by 3-inch height</li><li>Comes in 10-milliliter refill pack</li></ul></div></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br><img src='http://ecx.images-amazon.com/images/I/31u3dZDyJQL.jpg' noproxy></br><img src='http://ecx.images-amazon.com/images/I/41yIe%2B%2B31DL.jpg' noproxy></br><img src='http://ecx.images-amazon.com/images/I/31vQ9jJ1sRL.jpg' noproxy></br>