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=__**Water Test: Total, Calcium and Magnesium Hardness**__=

Hard water is a term that is often used when referring to level of dissolved minerals that are present in the water. Water that is considered to be hard, has a high concentration of these minerals. Water that is soft, has a low concentration of minerals. Water hardness is caused by the dissolving of minerals to form ions in the water. Two minerals, calcium and magnesium, typically come from limestone rock that had dissolved into the water. Areas that have high levels of limestone will tend to have high levels of calcium and magnesium.

Water hardness is an important biochemical aspect in the ecosystem. Calcium is one of the minerals that we measure when we detect water hardness. Fish and other species need this important mineral in their daily lives. Some of the reasons they need it is for bone formation and proper blood clotting. This is why it is important that safe levels of these mineral ions are present in the water.

Hard water is also linked to pH levels. Water that has a high levels of hardness, tend to be high in pH as well. This is because the dissolved minerals act as a buffer and can reduce the amount of acid in the water. Water that is low in levels of hardness, tend to be low in pH because there are not as many minerals to help buffer the acid.

Please refer to these and other resources to help you with your research.

Resources [|Understanding Water Hardness] [|USGS - Water Hardness and Alkalinity]

1.) What does it mean when your water is considered to be hard? 2.) Why are water hardness levels important to the ecosystem? 3.) What important ion do fish need to survive? 4.) What are some potential sources for Magnesium and Calcium ions? 5.) Predict: If you have high levels of hard water, how would the pH of the water be affected.

Procedure See attached procedure and safety information below. 1.) What are the safety concerns for the chemicals in this lab? 2.) How do you calculated Magnesium Hardness

Data

Analysis Using the internet and other resources, determine what levels of calcium and magnesium hardness are safe for aquatic organisms. (BE SURE TO CITE YOUR SOURCE!)

Conclusion 1.) What were the challenges of this particular water test? 2.) What might you do differently next time?