Calcium Hypochlorite: Also common known as “cal hypo,” this shock is the most powerful and fastest acting shock available. Both an oxidizer and sanitizer, cal hypo is quick dissolving and is the most frequently used in the pool industry. It will slightly raise your pH, so make sure you adjust pH while using it.
Many people believe that liquid chlorine raises the pool water pH. It does not. Most liquid chlorine (sodium hypochlorite, 12.5 percent) has a pH of about 13; cal hypo has a pH of 11.8 and lithium hypo has a pH of 10.8. These are all very alkaline so it is logical to think that when added to water they will raise pH.
In addition to raising available chlorine, cal hypo boosts pH, alkalinity and calcium hardness (CH) levels. Trichlor has the opposite effect on pH and alkalinity — reducing it.
The presence of caustic soda in sodium hypochlorite means the pH of water increases when the chemical is added.
To raise or lower the pH of a Mash , additions of calcium carbonate (to raise pH) or calcium sulfate / calcium chloride (to lower pH) are recommended. If these are not available, or if you are brewing with very soft water, then the addition of phosphoric acid can accomplish acidification of the mash.
Calcium carbonate treats water with a pH greater than 6 and synthetic magnesium oxide will treat water with a pH below 6. Untreated water flows through the filter, which is filled with calcium carbonate (limestone) or a synthetic magnesium oxide medium. This material dissolves in the water and raises its pH level.
Increasing calcium chloride from 0 to 50 mmol/dm' decreased the maximum rate of casein aggregation by 94% and decreased the pH from 5.2 to 4.5 at which aggregation was initiated.
It acts as a strong base since it readily accepts H+ When dissolved in water, the hypochlorite anion accepts a proton from H2O, liberating an OH– ion.
Using liquid chlorine raises the pH of the water.
When added to water, liquid chlorine (which has a pH of 13) makes HOCl (hypochlorous acid – the killing form of chlorine) and NaOH (sodium hydroxide), which raises pH.
Obtaining a pH level requires an aqueous solution because pH is the result of the comparative amount of free hydrogen and hydroxyl ions in a water-based solution. Adding baking soda with its pH of 9 to water with a neutral pH of 7 raises the pH level of water.
Well, it works just like any other type of chlorine. After adding calcium hypochlorite to your pool, the chlorine quickly reacts with the water to form Hydrochloric Acid.
The key difference between calcium hypochlorite and sodium hypochlorite is that calcium hypochlorite contains two hypochlorite anions associated with one calcium cation whereas sodium hypochlorite contains one hypochlorite anion associated with one sodium cation.
Cal hypo does not contain stabilizer (cyanuric acid), though it can be stabilized toward sunlight in recreational water through the use of cyanuric acid. You can buy it in slow dissolving tablet forms, or more rapidly dissolving granular forms, depending on your needs.
Liquid chlorine and bleach (sodium hypochlorite) have a pH of 11.0 to nearly 13.0 so it is logical to think that they will raise the pH of the pool water. The fact is that initially or upon addition liquid chlorine raises pH because sodium hydroxide (lye) is made.
Some commercial bleaching powders are prepared as physical mixtures of Calcium chloride and Calcium hypochlorite. Aqueous solutions of calcium chloride hypochlorite are equivalent to solutions of calcium hypochlorite with Calcium hydroxide. Both contain about 60-65% available chlorine.
Calcium Hypochlorite is commonly seen as granular Chlorine but also is in puck/tablet form. Calcium Hypo has an AC of 40-78% and it the most popular of the Chlorines.
To bring down pH, use a made-for-pools chemical additive called pH reducer (or pH minus). The main active ingredients in pH reducers are either muriatic acid or sodium bisulfate (also called dry acid). Reducers are readily available at pool supply stores, home improvement centers and online.
A high pH level can be caused by several factors, the main culprits being additional chlorine stabilizers and sudden increases in temperature. In addition, high pH runs a risk with your chlorine, as your chlorine will no longer disinfect fully. There are also physical consequences of high pH for swimmers.
Chemically, this has to do with the relationship between the two constituents of chlorine that together are often referred to as “free chlorine”—hypochlorus acid and hypochlorite ions. Hypochlorus acid is the more effective disinfectant and it dominates at lower pH levels, so a lower pH is preferred for disinfection.
Calcium Hypochlorite (Dry Chlorine)
Calcium hypochlorite is a stable, concentrated, dry source of hypochlorite frequently used for chlorination of swimming pools. The usual formulation contains 70% concentration of chlorine.
Experiments showed that pre-chlorination using calcium hypochlorite improves coagulation and flocculation processes and enhances algal removal through sedimentation.
Most commercially sold cal hypo products contain anywhere between 65% and 75% chlorine in the mixture. For every 1ppm of free chlorine (FC) in your pool, calcium hypochlorite adds about 0.8 ppm of calcium into the swimming pool water.
Calcium chloride, calcium nitrate and calcium sulfate are all considered to be neutral salts, in that they will not directly raise or lower the soil pH.
The pH of the original calcium chloride hexahydrate solution was indeed too low (3.7 at 20 ºC).
Calcium is an important determinant of water harness, and it also functions as a pH stabilizer, because of its buffering qualities. Calcium also gives water a better taste.