Calcium Chloride for Pools Vs. Roofs

Pools

• The "hardness" or "softness" of water is a measure of the amount of calcium and magnesium ions in it. Calcium levels in pools should be somewhere in the neighborhood of 200 to 400 parts per million. If the water is too soft -- or, it has too little calcium in it -- it becomes more corrosive, so you can add calcium chloride to correct the calcium level and solve the problem.

Types

• Many supermarkets sell calcium chloride as ice melt. You should not use this kind in your pool, however, because it contains impurities. When buying for your pool, head to your nearest pool supply store and look for pharmaceutical grade CaCl2 instead. Unless the product you purchase advises otherwise, you can generally assume 10 pounds of calcium chloride will raise the calcium hardness of 10,000 gallons of water by 80 parts per million.

Roof

• Calcium chloride works well in your pool, but applying it to your roof has some disadvantages. The calcium chloride will definitely help melt accumulated ice and snow, but the high concentrations of CaCl2 can accelerate corrosion and damage shrubbery that lies beneath gutters and spouts. The same is true for sodium chloride, which is another, more common de-icing agent. A safer de-icer for your roof is a salt called calcium magnesium acetate; you may be able to find this de-icer in local hardware or home improvement stores.

Options

• Travelers' Claim and Risk Control notes that rock salt is more damaging to your roof than calcium chloride; moreover, calcium chloride can potentially be a viable way to deal with ice dams. If you fill a stocking with calcium chloride and put it on the ice dam, it can help you melt a passage through the ice. If you're using calcium chloride in this capacity, you don't need the pharmaceutical grade you would buy for your pool -- calcium chloride ice melt is just fine.