b'Pool Cheat Sheet Above pH 7.8 conditions also become very favourable for algae blooms. Maintaining pH in a pool is therefore critically important, as it aids sanitation, swimmer comfort & equipment lifetime whileoptimising running costs. Pool Magic Soda Ash is used to raise pH levels, while Pool Magic Hydrochloric Acid or Pool Magic Dry Acid is used to reduce them. Total Alkalinity Total alkalinity is a measure of the alkaline substances in the water. The level of TA in a pool should be kept between 80 - 150ppm, allowing for variation depending on pool surface type. Within this range, TA acts as a buffer that prevents the overall pH to rocket upwards or downwards wildly. Think of it as a seatbelt that holds your pH in place & optimises chlorine efficiency. The effects of TA being too low are: pool surfaces can etch, metals can corrode, floor & walls can stain, water can turn green & eyes can burn. The effects of TA being too high are: the pH becomes hard to adjust lower, the water becomes cloudy, tests will show a constant need for acid, & chlorine can become less effective. Pool Magic Buffer is used to raise the TA level, while Pool Magic Hydrochloric Acid or Pool Magic Dry Acid will lower it. Calcium Hardness Calcium hardness relates to the calcium mineral content of the water. Hardness levels should be kept between 180-350ppm, allowing for variation depending on the pool surface type. Recall that optimal chlorination happens at pH 7.2 - 7.6, and that we want Total Aklinity to buffer the pH at that level. However, at those levels it triggers a demand - think of it as a thirst - for calcium in the water. If you have a calcium- rich marblite pool surface, then the water will try scavenge calcium from the walls, causing surfaces to etch, & metalsto corrode. Optimal calcium hardness prevents imbalance & quenches this calcium thirst. On the other hand, if the calcium levels are too high, the water will expel it from solution - causing calcium-scale precipitate to form around the pool. Filters & pipes may clog, water can become cloudy & eyes may burn. Pool Magic Calcium Increaser is used to raise the level, but lowering generally involves draining water,& topping up with fresh water.pH (Continued) Free Chlorine The presence of chlorine is not a sign of disinfection capability. Whatever the source of chlorinemolecules (e.g. salt, chlorine gas, liquid chlorine or solid chlorines like calcium hypochlorite orTrichlor), in solution they all combine with water to form the disinfectant Hypochlorous acid (HOCl). Only Free chlorine will form the Hypochlorous Acid (HOCl) you need to kill bacteria & viruses, and oxidise away contaminants & waste products. To both sanitise an oxidise a pool, Free Chlorine Residual of at least 1ppm is required at the correctpH (see pH below) When free chlorine combines with the organisms & contaminants (urine, sweat, make-up,hairspray, etc) its job is done, and it becomes combined chlorine. However, when water conditions are not optimal, chlorine levels are too low or when bather loads & other waste levels are too high, it can prevent Free chlorine from forming HOCl. Instead, the chlorine combines with waste & other chemicals to form compounds that are not effective disinfectants. Combined chlorine - the opposite of Free chlorine - has minimal sanitation & oxidising capability. Total Chlorine Total chlorine is the sum of both free & combined chlorine. Ideally the total chlorine reading should equal the free chlorine reading (known as breakpoint chlorination). pH pH, or potential hydrogen, is measured on a scale of 0-14, with 7 being neutral. Solutions lower than 7 are referred to as acidic, & solutions higher than 7 are referred to as alkaline. The pH of water determines how effective chlorine will be. Free chlorine will form the maximum possible amount of hypochlorous acid (HOCl) disinfectant at pH 7.0 & below. However, below pH 7.0, chlorine becomes too aggresive (staining) & volatile (loss to atmosphere) for swimming pool use. Therefore, the ideal recommendation for pH in a pool is 7.2 - 7.6 on the scale - low enough to optimise Free chlorine / HOCl formation without risking unwanted adverse effects.Combined Chlorine178'