Algae, bacteria, or fungus growth. Debris or contaminants from winter or periods of inactivity. Heavy pool usage or high
Chlorine demand occurs when there are a lot of organic and inorganic chemicals, minerals and other types of matter in swimming pool water that the chlorine is struggling to neutralize.
It can be one of two things, either your cell is not producing or you have what is called a chlorine demand although this is rare on pools with chlorine generators. Be sure that you were tested for phosphates. If phosphates are in pool water then the cells do not produce the chlorine needed.
Debris or contaminants from winter or periods of inactivity. Heavy pool usage or high bather load, especially during summer. Biofilm or organic material in the water, such as sunscreen, leaves, or algae. Pool covers trapping chlorine and causing it to dissipate more rapidly.
To Eliminate Demand
Shock the pool with 3 lbs. of SuperSonic per 10,000 gallons of pool water. Circulate the water continuously.
Bacteria, algae and microscopic contaminants, such as urine, sweat, sunscreen and beauty products, take a toll on your swimming pool's water chemistry. These substances, when present in your pool water, accelerate chlorine demand and can affect your chlorine's ability to maintain properly sanitized water.
Too much Stabilizer: A chlorine lock can occur when you have added too much cyanuric acid, or stabilizer, into your pool water. Stabilizer is a chemical intended to protect chlorine from burning off too quickly from UV rays. If you get too much of it, it can completely block your chlorine and make it ineffective.
There are a few possible causes for murky water, with the most common causes of a cloudy pool being a low runtime, chemical imbalance, algae, excess debris, and excess calcium. 1 Each problem has a diagnosis and treatment but generally should clear up in a few days with proper attention.
Make sure the pool is clean and chlorine is at the proper level. Read the dosage on the bottle for recommendations. For liquid or powder stabilizer, add to the pool by walking around the perimeter and slowly adding stabilizer along the edges. If using powder stabilizer, brush pool down to promote mixing.
This powerful compound is the real bacteria-fighter, destroying the cell walls of harmful microorganisms and keeping your pool water sanitized.
If you just added chlorine or a chlorine-based shock to your pool and you still have a low chlorine level, there's a chlorine demand problem. In order to cure chlorine demand, triple shock your pool with calcium hypochlorite or cal-hypo shock.
Raising pool chlorine can be much easier than trying to lower chlorine levels. Simply adding chlorine in the form of chlorine tablets, granular chlorine, liquid shock or powder shock will increase the total amount of chlorine within the pool.
Surely it's safe to swim in. FALSE. It doesn't matter how much time and effort you put into skimming, brushing, vacuuming, circulating, and filtering your pool. If there's not enough chlorine in the water, your pool's not actually clean, and the water's not safe.
Shocking is crucial for removing any pathogens in the water and making a pool safe for swimming. It also involves using heavy-duty chemicals, including chlorine, so it's best to wait at least 24 hours after you shock a pool to go swimming. Going in too soon can potentially cause skin, eye, and even lung problems.
The consistent inability to maintain chlorine levels is also called “chlorine demand” and is most often caused by a high level of inorganic and organic contaminants in the water. Those contaminants force the chlorine to work extremely hard to oxidize them, leaving little chlorine to protect swimmers.
If a leak develops in a chlorine system, shut off the cylinder valves and ventilate the area to the outdoors prior to repairing the leak. Should a major leak develop which can not be controlled, clear the area of personnel, and exhaust the fumes to the outdoors.
Direct sunlight (UV)
Direct sunlight breaks down chlorine.
Skim your pool water at least once a day and vacuum the interior of your pool once a week to remove debris. This will give your chlorine less to keep clean, making it last longer than it would without maintenance.
It could be chloramines, combined chlorine, high TDS, low cyanuric acid, unbalanced water, phosphates, or nitrites/nitrates. Water analysis will reveal the usual causes.
Basic Checks First: Filter Run Time: Make sure your filter is running for at least 10 to 12 hours total per day, specifically during the daylight hours when the sun is out. Circulation: Check that you have strong circulation while on high speed.
Low/No chlorine production
The factors that affect chlorine levels include the summer heat, poor filtration, bather load, and the frequency of use. It's also possible that the time period you set is too short, the chlorine output level is too low, or the filter needs backwashing.
Thankfully, by far the most common reason why pool shock wouldn't work is very straightforward. It's all to do with your pool's pH. Pool expert Rafi Friedman told me that 'Pool shock works best with a balanced pH. If your pool's pH is too high or too low, the shock won't be effective.