Answer: Don't shock the pool until pH and Alkalinity are balanced. Both your pH Alkalinity are still too high: Just add more muriatic acid to bring down TA between 80 - 120 ppm, pH between 7.4 - 7.6.
Another cause for high alkalinity can be when you shock the pool. While this is performed to quickly rid the pool of pollutants, chlorine-based pool shock is highly alkaline, and can raise the water's total alkalinity level in the process.
When you shock a pool, you test and adjust the pH level for a reason. With that said, if you shock a pool outside of the 7.2 to 7.4 pH range, not only will you waste a significant amount of the chlorine used, you will also end up with cloudy water.
Increasing alkalinity is as easy as adding more carbonates to the water. The safest, most cost-effective, and popular product is sodium bicarbonate (aka baking soda, or bicarb). Sodium bicarb is great for raising alkalinity, and also slightly raises the pH of the water, because its pH is only about 8.3.
Raising PH Level
PH Plus will increase your Alkalinity level slightly too so keep an eye on this as remember Total Alkalinity is the buffer to allow your PH to be set.
What happens if too much shock is added? You cannot overshock a swimming pool or add too much. Adding too much shock or overshocking your pool will kill off algae. The negative of adding too much shock is it will upset the chemical balance of your pool.
Chlorine is a sanitizer, and (unless you use Baquacil products) is necessary for maintaining a clear and healthy pool. Shock is chlorine, in a high dose, meant to shock your pool and raise the chlorine level quickly.
The best time of day to shock your pool is in the evening. This is because the sun's rays can affect the effectiveness of the chlorine by dissolving it too quickly, before it has a chance to rid the pool of contaminants and clean the water.
Most people know that chlorine is an important chemical in keeping pool water safe for swimming. But adding too much chlorine can lower your pool's pH as well as its total alkalinity. When alkalinity falls, it is more difficult to maintain a stable pH.
To lower the alkalinity in your pool, try using a strong acid like muriatic acid, sodium bisulfate, or sulfuric acid all of which will lower the alkalinity. If your pool water is a little murky or your pool filters seem to be plugged with calcium deposits, then your pool may be suffering from high alkalinity levels.
There is a perfectly natural reason for this: evaporation and agitation of your water leads to a drop in the total alkalinity. If you consider the composition of the total alkalinity in detail, it constitutes the water's carbonate and bicarbonate content.
Check Total Alkalinity (TA) first, then adjust for proper pH range. Proper TA will buffer pH, that is, it will help to prevent pH fluctuations. Use fresh, high quality test strips. Excessively high bromine or chlorine levels can result in false pH and TA readings.
NATURAL FACTORS INFLUENCING ALKALINITY
Phosphates, limestone, and borates give the water a higher alkalinity and buffering capacity. Seasonal weather - spring snow melt and rain can increase runoff which generally also increases acidity, in turn decreasing alkalinity.
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.
Liquid chlorine and granular shock have the same active chemical that sanitizes your pool, what changes is the strength and the way you use it. Liquid chlorine is less costly, unstabilized and comes in liquid form. Granular shock is stabilized and comes in a solid form that dissolves in your pool.
Backwash only as needed. Brush the pool vigorously, several times after shocking the pool. Do not use a solar blanket until chlorine and pH level are normal. If chlorine level drops to zero within 24 hours, Repeat the shock treatment.
This is because when you mix chlorine and algaecide together, it renders both of them useless. Hence, you should first shock the pool and wait for the chlorine levels to fall below 5 PPM.
It's pretty tough to over-shock your pool; shocking your pool two days in a row with the proper dosage for your pool volume shouldn't be a problem – and in fact, is sometimes even needed to rid your pool of algae and other contaminants.
Pools can immediately turn green after shocking when they have metals like copper or iron in the water. These metals oxidize when exposed to high levels of chlorine which makes the pool water turn green. Metals in the water are caused by some algaecides and using well water.
It's often recommended to shock your pool once a week. If you don't do it every week, you should at least do it every other week. This is necessary to maintain your pool's water chemistry. If you have a lot of people over in your pool or have a party, you may want to shock your pool more frequently.
This means you buy more chlorine and waste more time trying to get to an adequate concentration level with the substance. Asides its effects on your pool, a low alkalinity swimming pool is unsafe for swimmers as the acidic water can cause nasal, eye, and skin irritations.
If you want to raise your pH and alkalinity together, use soda ash (sodium carbonate). If your goal is to raise alkalinity only, use baking soda (sodium bicarbonate).
Alkalinity can be easily replenished in an aquarium by periodically exchanging a portion of the tank water with new water with a moderate total alkalinity or by adding chemical buffers, such as sodium bicarbonate (baking soda), to the water.