Higher levels may result in damaged swimwear and a spa pool cover or skin irritation. If your chlorine levels are over 10 ppm, do not under any circumstances use your spa until the chlorine has been neutralised.
The maximum safe chlorine level is 3 parts per million (ppm). Anything above 5ppm is considered a hazard and should be addressed immediately. If you find numbers as high as 7-10ppm, the pool should not be used until chlorine levels return to safer levels.
It's fine. My family swims with 8-10ppm Chlorine all the time. Your swimsuits will smell nice and chlorinated if you hang them up to air dry afterwards.
The Centers for Disease Control and Prevention (CDC) recommends a safe chlorine level of up to four milligrams per liter or four parts per million. These measurements are considered safe amounts of chlorine in drinking water where harmful health effects most likely won't occur.
Once the chlorine level has dropped below 5.0 ppm it should be safe to swim in. That's barely more chlorine than the tap water we use for bathing, cooking, and drinking.
Chlorine levels between 1-5 ppm are generally acceptable, although 3 ppm is ideal. If your chlorine levels are above 6 ppm, you'll most likely bleach your swimwear or experience serious skin irritation.
There are really 3 main reasons to shock a pool or spa, raising the Free Available Chlorine level high enough (10–30 ppm) to oxidize or destroy the offending contaminants.
A concentration of 34 to 51 ppm has been reported to be lethal in 1 to 1.5 hours [Freitag 1941] while 14 to 21 ppm has been suggested as being dangerous within 0.5 to 1 hour [NPIRI 1983].
Natural dechlorination will occur over time and chlorine will dissipate when exposed to the air and sunlight. This process can take 5-10 days, depending on a variety of factors, including pool size.
A good chlorine level is between 1.0 and 4.0 parts per million (ppm), while the pH should be between 7.2 and 7.8. Together, they keep bad bacteria at bay: If pH goes up too high, chlorine's germ-killing power deflates.
The effect of excess chlorine in pools is an alteration in pH levels of pool water, making it more acidic. Signs of high chlorine levels can include itchy sensations in the eyes, nose and throat, nausea, vomiting, dizziness, lung irritation, and skin rashes.
Dilution is one of the most straightforward methods. Adding more water without chlorine effectively lowers the concentration in the pool. Partially draining the pool and then refilling will take some time, and the added water will also need to be mixed in and tested again once settled.
Safe Chlorine Levels in Drinking Water
The World Health Organization set a health-based guideline on how much chlorine is added to drinking water worldwide. Their maximum chlorine value is 5 ppm in drinking water.
Prevent & Remove Algae
Light green or isolated algae may only require 10 ppm (parts per million) of added chlorine to eradicate. Medium green or yellow blooms may need double the dose. For dark green or black algae, adding enough pool shock to reach 30 ppm may be necessary.
Eye and Skin Irritation: Red, itchy, and watery eyes, along with skin redness and irritation, are common signs of chlorine exposure. Headache: Some individuals may develop headaches as a result of chlorine exposure. Fatigue and Weakness: Feeling tired and weak is another possible symptom of chlorine poisoning.
Typically a high Free Chlorine level means that your Cyanuric Acid level is too high. For your Free Chlorine (FC) to be effective if you are using Cyanuric Acid (CYA) as a stablizer, you will need to have your FC at 7.5% of your CYA level.
Statistically, a pool without chlorine is more likely to make you sick because of the possibility of being exposed to the things not contained or killed by chlorine. Remember, your skin is porous, so microscopic impurities can pass through. A pool sans chlorine is akin to a big puddle of murky water.
There are three main ways to remove chlorine from tap water. Leave it to stand in the open air for up to 24 hours, boil the water, or install a drinking water filter or whole house water filter that contains a carbon block water filter cartridge.
If you're adding your regular doses of chlorine (i.e. not shock), a good rule of thumb is to wait 4-8 hours or until the water has experienced 'turnover' and has been cycled through the whole system. If you're shocking your pool, you'll have to wait longer.
When free chlorine is over 5.0 ppm, swimmers may experience itchy skin, irritated eyes, and/or dry hair. Pools will naturally gas-off chlorine from the surface, and very high levels can irritate airways and lungs. This is especially true for indoor pools. At chlorine levels over 10 ppm, swimsuits can begin to fade.
Health inspectors look for chlorine solutions to have a minimum of 50 PPM concentration of chlorine. Best practice requires 100PPM. Either level can be confirmed by test strips. Chlorine solutions are generally corrosive with long term usage on equipment, and may damage plastic and rubber parts with continued usage.
Shock Your Pool: The best way to solve low free chlorine levels is through shock treatment. Shocking is a concentrated dose of chlorine added to raise the level quickly and oxidize existing contaminants.
CDC recommends pH 7.0–7.8 and a chlorine concentration of at least 1 ppm in pools and at least 3 ppm in hot tubs.
Hot & Rainy Months: Weekly
During the hotter months of the year, or when the forecast shows a chance of rain, shock your pool weekly. These conditions can significantly increase the chance of algae growth, and a weekly dose of shock will help keep the green away.
If you test your pool water and can't get a chlorine reading at all it may be due to very high chlorine demand. High chlorine demand is the inability to keep an adequate level of chlorine in the pool water even though the water appears to be balanced and properly maintained.