What Happens If Free Chlorine Is Low
You might be familiar with at least one of the common side-effects of swimming: sore eyes, skin irritations, fading swimming costumes, and that odd smell that lingers until we take a shower. Those are some of the effects of low levels of free chlorine in the water.
When free chlorine levels are low, the little amount left in the pool water will be used up quickly by fast-growing microorganisms like bacteria, and this makes the pool unsafe for swimming.
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Its Important To Keep A Close Eye On Your Free Chlorine
So be sure to pay close attention to the free chlorine level in your pool every time you take a test reading of the water. You now know how important it is to know the amount of chlorine in your pool thats free and available to act as a sanitizer.
Keeping your free chlorine at the proper level will help your pool water be safer to swim in and keep it clear and pleasant to look at too. Staying on top of your free chlorine level regularly will also prevent unnecessary problems in the future.
Why Your Free Chlorine Reading Is Key
If your chlorine isnt working effectively, one of the easiest ways to narrow down the cause of the problem is to test your water for free chlorine.
This result will tell you a LOT about whats happening to the chlorine in your water.
Specifically, if youre seeing no free chlorine in your pool, even after recently adding chlorine to your water, it means your chlorine is either burning off or being consumed very quickly.
Alternatively, if youre seeing a free chlorine reading above zero despite having less-than-ideal water conditions, that can only point to your chlorine being inhibited by the conditions of your water.
Well talk about possible causes and fixes in the next sections, but its important to first run this test so you have a general idea of whats going on.
Note: When troubleshooting issues with your pool chemistry, we strongly recommend using a liquid drop kit for more accurate testing.
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How Can Free Chlorine Be Lowered In Pool Water
In outdoor pools free chlorine will naturally decline 2-4 ppm a day due to the sun.
There are chlorine neutralizers most likely contain sodium thiosulfate.
- Add Sodium Thiosulfate, aka Chlorine Neutralizer for instant reduction.
- Add Ascorbic Acid, aka Vitamin C to remove chlorine.
- Add Hydrogen Peroxide, aka H2O2, to breakdown chlorine.
- Remove chlorine naturally with sunlight, aeration and agitation of the water.
Sodium Thiosulfate, add 2 oz per 10,000 gallons of pool water to lower chlorine level by 1.0 ppm.Probably the cheapest and most reliable method to lower chlorine levels, in pools or spas.
Ascorbic Acid yes, granular Vit C! Add 32 oz per 10,000 gallons of pool water to lower chlorine level by about 9 ppm.
Hydrogen Peroxide use 1 gallon of Aqua Silk Oxidizer per 10,000 gallons of pool water to lower chlorine level by 55 ppm. For spas, use 3% drug store peroxide, 2 ounces per 100 gallons of spa water, to lower chlorine level by about 10 ppm.
For Sodium Thiosulfate, add about a cup of the dry white crystals per 5,000 gallons of pool water, or 1 oz per 100 gallons to lower chlorine by 10 ppm. Check your pool water pH and adjust to within label instructions, and add directly to the pool or spa.
Another good resource is this sodium thiosulfate calculator on Koiphen.com enter your pool size in gallons and the current chlorine level in ppm, and it tells you how many ounces or grams of Sodium Thiosulfate to add to reduce chlorine to zero.
Does Chlorine Consumption Change With Water Temperature
Warmer water losing more FC due to sunlight than colder water is not true.
Chlorine loss from the UV in sunlight does not depend on temperature because it only depends on the number of photons per area entering into the pool and on the concentration of chlorine. The photons of light are traveling much faster than the molecules containing chlorine so the temperature which relates to the speed of those chlorine molecules is irrelevant. From the point of view of the photons, the molecules of chlorine are essentially standing still so the cross-section of those molecules which is the area with which the photon has a quantum probability of reacting with the molecule is independent of the temperature and only related to the concentration of such molecules in the water.
Chlorine consumption that is related to temperature is for chemical reactions with chlorine such as oxidizing pool covers, bather waste, pollen, leaves, algae, etc. And yes, algae grows faster in warmer water but such consumption won’t matter if there is sufficient FC/CYA since algae will get killed before it can reproduce so the rate will be based solely on the rate of blown-in algae spores which is usually not measurable .
A pool with a solar cover that is opaque to UV would lower the loss of chlorine from sunlight that is not temperature dependent but would increase the loss of chlorine from oxidizing the cover which is temperature dependent.
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How To Determine The Correct Swcg Percentage Setting
To know the right SWCG percentage setting to produce the ideal level of chlorine for your pool, you have to be aware of few things and they are:-
1). Determine the right FC level for your pool. FCL in your water goes hand in hand with the level of Cyanuric acid in your water.
2). Measure the actual FCL in your water and compare it with the appropriate FCL in your SWCG. Testing FC level should be done in the evening so that when its low, you adjust your chlorine generator percentage setting appropriately.
3). If the level of FC in your water is low, increase the percentage of your SWCG to produce more chlorine and reduce the percentage if the FCL is high.
4). If the FC level is not balanced within an hour, wait for 48 hours and repeat steps 2 and 3 until your FCL is balanced with the Cyanuric acid level in your water.
What Is A Fas
A FAS-DPD test stands for ferrous ammonium sulfate and N, N-diethyl-p-phenylenediamine, which refers to the chemicals used to measure your FCL and CC levels. Next, add the DPD to your pool water sample, which will react with the chlorine to produce a pink color. Next, you will want to add in the FAS drops until the pink color disappears. So the number of drops needed to turn the water colorless determines your CC levels.
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When Do I Need To Shock My Pool
On average it is recommended that a pool owner shock their pool at least once a week during peak swimming season. However, it should be noted that the need to shock your pool should really be dictated by how often and how many bathers use your pool in direct correlation to weather conditions such as long periods of sun or rain.
As a general guide, you should shock your pool when:
- Algae begins to grow in your pool
- The free chlorine level of your pool measures zero
- The combined chlorine level rises above 0.5
What Does Hold Chlorine Even Mean
Well, there are two ways to interpret this:
The first is if youve tested your water soon after adding chlorine only to find youre somehow seeing no free chlorine in your pool.
The second is if your water always seems to look dirty or green despite adding plenty of chlorine and getting a normal free chlorine reading.
Either of these scenarios is bad news for you as a pool owner, but they do each offer a clue as to what might be causing your pool water to ignore chlorine, and how you might go about fixing it.
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How Do You Shock A Hot Tub With Chlorine Granules
If you are using chlorine granules, you will still use the steps illustrated above. The only difference is that you will be dissolving about 1 oz of chlorine granules in every 500 gallons of hot tub water.
Aside from that, every other step is the same. Make sure that the granules dissolve completely before you add the mixture to the hot tub.
Granules can easily drop to the bottom of your spa and damage it if you add them directly.
How To Raise Free Chlorine In A Pool
If youve not cleaned your pool yet and theres a lot of debris, your free chlorine level is likely low because its busy working on cleaning all the contaminants from the debris. Clean your pool and remove debris, then test the chlorine level.
Then, test your water. Youll want to make sure your pH, alkalinity, and cyanuric acid levels are within range. If you need help balancing your water chemistry, be sure to check out our guides on pH and cyanuric acid.
Once your pool is free of debris and your other levels are balanced, its time to shock your water.
When you shock your pool, youre adding enough chlorine to reach a chlorine breakpoint. This raises your pools free chlorine levels to 10 times or more over the normal amount.
There are multiple types of chlorine pool shock and each one can affect the other pool chemicals in the water, like your pH levels. Keep in mind that using a non-chlorine shock will decrease your combined chlorine but it will not raise your free chlorine level. Thats because the oxidation in a non-chlorine shock helps break up contaminents without adding chlorine.
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How To Test Pool Chlorine With Test Strips
There are two ways to test your pool chlorine: test strips and test kits. Test strips are a bit easier and more convenient to use than test kits. Test strips tend to be the method of choice for non-professional, pool owners. Test strips often come in small, cylindrical containers that feature color scales on the outside of the container that correspond to each of the chemicals tested on the strip. To conduct a test, simply take one of the strips from the container and dip it in your pool water. The container should include instructions on how long to hold the strip under water, as well as how long to let the strip rest before comparing the test colors to the color scale. To test chlorine, match the appropriate test on the strip with the chlorine color scale on the container. The color will likely not be an exact match with any of the benchmark colors on the testing container. Use your best judgement to estimate the tested ppm based on the color of your test strip compared to that of the lighter and darker colors that most closely match yours.
Free Chlorine Vs Total Chlorine: Whats The Difference
Chlorine is a standard chemical element thats oftentimes used to provide people all over the world with clean drinking water. The reason that chlorine is highly effective and important for water quality monitoring is because its able to kill bacteria via a chemical reaction. Whether youre treating your swimming pool or work in a water treatment facility, using the right amount of chlorine can keep the water free from impurities.
When chlorine is added directly to pool water, it breaks down into such chemicals as hypochlorite ion and hypochlorous acid, both of which are effective at killing bacteria and various microorganisms. You should know the difference between free chlorine and total chlorine because each type of chlorine functions differently when in water. If you want to determine the effectiveness of your sanitation efforts, its important to properly identify the levels of free chlorine and total chlorine in the water.
Since chlorine is able to kill bacteria and similar microorganisms, its primary applications involve being used as a disinfectant in swimming pools and for the treatment of drinking water. Chlorine can also be used to make consumer products like textiles and paints. The vast majority of pharmaceuticals will use chlorine during the manufacturing of new medicines.
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Raising The Free Chlorine Level In Your Pool
If youve been having problems with your pool, one of the things you might need to do is raise the free chlorine level. But how do you do that? And why is it important?
So, how do you raise the free chlorine level in your pool? There are a few different ways to raise the free chlorine level in your pool. The first is by using chlorine tablets. Another way to raise the free chlorine level is by using chlorine powder. The third way to raise the free chlorine level is by using liquid chlorine.
In this blog post, we will discuss all of that and more! Well explain what chlorine is, how to determine the proper chlorine level for your pool, and how to measure the chlorine level in your pool.
Well also talk about the safest way to raise the chlorine level in your pool and the risks of improper chlorine levels.
Natural Chemistry Pool Perfect
Natural Chemistry Pool Perfect is a great way to complement chlorine sanitation by using enzymes to break down organic matter in the pool water, which allows it to dissipate more efficiently. Pool Perfect also contains compounds to reduce the phosphate levels in your pool that can increase the risk of algae growth.
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How Can Algae Grow In Water With Chlorine
Algae replication rates in warm water with insufficient sanitizer can be high enough such that there is a colony doubling every 2 to 4 hours . So in a 24 hour period with light available for more than 12 hours per day , algae grows very fast. The kill rate of any sanitizer is concentration dependent.
There’s not a lot of hard data on the CT kill rate for algae with chlorine, at least no easily available data, but once your active chlorine levels fall below 100 part per billion , the kill rates are well below the colony doubling times. So basically, algae can freely grow and thrive when there is sanitizer around.
Despite what you might think, your water is not one, homogenous mixture. While your water sample might say there’s 0.5ppm or 1ppm FC, there’s a very good chance that water right at the surface of the pool has no chlorine in it whatsoever and the water nearest the walls probably has much lower FC levels.
Why Don’t They Make Chlorine Tabs Without The Added Cya
Chlorine is a gas. It must be trapped by some material for a residential pool owner to use it. The most stable and economically viable are:
- Calcium – Calcium Hypochlorite, or
- Water – sodium hypochlorite .
There are cal-hypo tablets that do not contain CYA. You need a special feeder for them. They will add calcium to your water whoch can cause other unwanted problems as the pool CH rises. Calcium is the same as CYA, it does not go away without draining the pool water.
That is why a Salt Water Chlorine Generator is so easy and appropriate for a residential pool owner. You create your chlorine on site. Only thing you use is electricity. The device that creates the chlorine will last years if properly sized and water chemistry is properly maintained.
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Why Is Total Chlorine Lower Than Free Chlorine
Think of it this way: when a chlorine compound is added to swimming pool or spa water, it reacts with water to form the compounds known as hypochlorous acid and hypochlorite ion. … If the readings are the same, then no Combined Chlorine is present. The Total Chlorine level cannot be less than the Free Chlorine level.
Your Ph Level Is Too High
Chlorine works best at lower pH levels.
In fact, chlorine is incredibly potent in acidic water, but this would be a far lower pH level than youd want to see in a pool.
A pH level of 7.2 to 7.8 offers the best balance between chlorine effectiveness and swimmer comfort. Going over this pH limit inhibits chlorines sanitizing power too much, and leaves your water under-sanitized.
Unfortunately, pH will often rise over time, especially in a salt pool.
You can check your pH level with a test strip or liquid test kit, and any result over 7.8 should be acted upon.
Solution: Use muriatic acid to bring your pH level down into the appropriate range. Be aware, though, you may also need to follow acid with baking soda to rebalance your total alkalinity.
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How To Raise Pool Chlorine
The Association of Pool and Spa Professionals recommends keeping free chlorine between 2.0 and 4.0 ppm. The Center for Disease Control recommends free chlorine be kept above 1.0 ppm for pools and 3.0 ppm for hot tubs. If you find your free chlorine to be below these recommended ranges, it is important to add the appropriate chemicals to your pool to increase free chlorine back to the desired level.There are several chemicals that may be used to raise your free chlorine. These include chlorine gas, chlorine tablets, sodium hypochlorite , calcium hypochlorite , trichloroisocyanuric acid , dichlorine , and lithium hypochlorite. For more information about each of these sanitizing agents, read our post Types of Pool Chlorine Sanitizers.To determine how much sanitizer to add to raise your free chlorine to the desired levels, we recommend using the Pool Calcualtors free chlorine test. More information about how to use the test can be found in the video below. When your free chlorine levels get too low, we recommend using calcium hypochlorite to raise them back up.