“The algaecide will [deplete the existing] chlorine level dramatically, so you're going to have to add chlorine on top of it in order to activate the algaecide and to best utilize it in the pool,” Wilbur says. Preventing algae growth is more cost effective than having to treat an algae problem.
Risks and Side Effects: While metallic algaecides are effective, they can burn up chlorine residuals, leading to a 0-chlorine reading and potential algae regrowth. Over time, improper use can cause blue staining on the pool surface and damage to the plumbing or heater.
Symptoms/injuries : Causes severe skin burns and eye damage. Harmful if swallowed. Symptoms/injuries after inhalation : Irritation of the respiratory tract. Dizziness.
It is probably a combination of your water not being high enough in calcium hardness and the phosphate levels. Phosphates are algae food. Chlorine is a garden hose to a forest fire if there is way too much food for them in the pool water.
Dilute the pool
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. Furthermore, a large pool will require a sizable amount of water.
Sodium ascorbate will also neutralize chlorine. It is pH neutral and will not change the pH of the treated water. Sodium ascorbate is preferable for neutralizing high concentrations of chlorine.
In most cases, it takes 24-48 hours for chlorine concentration to drop significantly. If the water is too hot or the chlorine levels are too high, it may take longer for the chlorine to evaporate. You can speed up the process using a chemical oxidizing agent or diluting the water with fresh water.
Algaecide should be added to your pool water on a weekly basis. Preventing algae is the key to fun in your pool. Algaecides act as a backup to your normal sanitization program and prevent algae from starting and growing in the pool. Algaecide should be added after every shock treatment.
If your chlorine is already high or at the proper level then adding more chlorine or shock won't do anything to help the pool. If your pool is still green with a high chlorine level, it's best to increase your filter runtime and add an algaecide.
1) What is the difference between chlorine and shock? Do I need to use both? 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.
When algaecide treatments are applied incorrectly, one potential result is foaminess in the pool. Even high quality copper-based and silver-based algaecides will cause foamy pool water, if too much is applied.
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. Only then should you introduce algaecide to get the best results.
How long does it take for algaecide to work? Depending on the severity of the algae present in the water, it can take anywhere from a few hours up to 2 days for the algaecide to effectively work and kill the algae in your pool.
Direct sunlight (UV)
Direct sunlight breaks down chlorine. Without a stabilizer (cyanuric acid) in the water, as much as 90% of free available chlorine could be destroyed within just two or three hours.
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.
Can I add algaecide and shock at the same time? No. Let the shock try to fight the algae first. Add algaecide about 24 hours after shock to finish the job and prevent future algae blooms.
Use Hydrogen Peroxide.
Pool-grade hydrogen peroxide reacts with chlorine to produce water and oxygen. Just be sure to test your pH before adding it. It works best at pH levels of 7.0 or higher. It will also lower your pH after using it, so be sure to test and adjust your levels then too.
Algae can persist in a pool even after shocking. A green pool – especially one that turned green overnight or after rain, can also be from a pool pump that isn't properly circulating water or an issue with your filtering system.
If your pool is green, but chlorine is high, don't be too concerned. The most important test to take if your pool's still green after shocking is the pH level. Buy a kit or a test strip and test the pH because it will indicate whether you need to add other chemicals.
You should also run your filter for at least 8 hours after adding an algaecide to help remove any dead algae from your water. It's important to remember that algae can come back quickly, so once you get rid of it, be sure to take steps to prevent it from coming back.
Acid needs to be added when freshwater like rain fills up the pool, and algaecide is added when you have a green algal outbreak. However, it's chlorine that stops your pool from going green in the first place.
It is recommended to use a three-part algae treatment. 1) Brush and then perform a heavy shock on your pool. 2) Add an appropriate algaecide to the water while letting the pool equipment run continuously. And 3) vacuum your pool within 36-48 hours.
In most cases, high chlorine levels occur when too much pool shock or too much chlorine is added to the pool—either due to a one-time mistake or from long-term buildup. Check for a dispenser malfunction, as this is another common way to over-chlorinate a pool.
If you need to quickly lower chlorine levels in your hot tub, use a chlorine neutralizer, dilute the water with fresh water, or leave the cover off and run the jets to let the chlorine dissipate. These methods can help reduce chlorine levels to the recommended range of 1-3 ppm.
A good shock product should raise the free chlorine above 5 parts per million for several hours to destroy bacteria and chloramines. Keep in mind, if you have visible algae of any kind (black algae, mustard algae or green algae), you may need to double or triple the normal dosing of pool shock to eradicate the problem.