Chlorine lock is a term that’s well-known for the pool owners. If you add excessive pool stabilizer or Cyanuric acid to the pool, the pool gets the chlorine-lock state. Cyanuric acid protects the chlorine molecules from ultraviolet rays. In the presence of CYA, the sun rays can’t eat up the chlorine molecules rapidly. If you add too much pool stabilizer, the cyanuric acid in the pool stabilizer locks the chlorine molecules completely. So, it becomes useless.
A Chlorine Lock occurs when your Total Chlorine is Higher than your Free Chlorine, resulting in High Combined Chlorine. This usually happens when water is not properly shocked weekly, and when the proper sanitation residual isn’t consistent.
Types of Chlorine
There are three types of Chlorine to test for, that not all at-home test strips or kits accurately test.
- Free Chlorine is the chlorine that sanitizes.
- Total Chlorine is all the chlorine in the water – even the chlorine that’s wrapped up in organic or inorganic materials.
- Combined Chlorine is the Total Chlorine minus the Free Chlorine. The difference is all the organic and inorganic chloramines. Combined Chlorine should ideally be at zero. Total Chlorine and Free Chlorine should be equal to each other.
In order to get rid of a Chlorine Lock, you must achieve Breakpoint Chlorination. To achieve Breakpoint, the Free Chlorine in the water must be raised to about ten times the amount of Combined Chlorine. If not enough Free Chlorine is achieved, any Chlorine added goes straight to Combined. Also, if you add too much, the Chloramines may evaporate, and then re-dissolve, making no change.
Ways to Getting Rid of Chlorine Lock
There are a few ways of ridding a lock, but the most effective way we have noticed is through dilution, in part with oxidizing, and super chlorinating. Also, this is the most cost-effective. Sometimes Locks can be difficult to break and can take a few attempts if using chemicals alone. We always recommend retesting 48 hours after super chlorinating, to allow Chlorine to burn off, and to avoid false readings.
Method # 1: Partial Drain Pool
Partial drain pool will get you rid of chlorine lock to some extent. Don’t drain it completely because you need to start from zero and it’s time-consuming and costly.
- Drain 1/4 portion of water from the pool.
- Now refill the water to the level.
- If you refill 1/4th of the water, you need to test the chlorine again. The test will confirm whether the issue has been resolved or not.
- It will give your pool sort of a refresher and allow you to start with some cleaner water.
- If the issue persists, drain some more water and test the chlorine again.
- You need to repeat the process until the total chlorine and free chlorine levels become equal.
Method # 2: Chlorine Shock
Chlorine shock is a straightway method to break chlorine lock. In this method, you add a huge quantity of chlorine to break up the molecules of chloramines. The product used in it is known as chlorine shock.
Before adding chlorine shock, check the pH level. It should be balanced and between 7.2 – 7.6.
Method # 3: Non-chlorine Shock
It’s another effective way to get rid of chlorine lock in the pool and hot tub. Non-chlorine shock restores the chlorine balance and oxidizes the water. Resultantly, the water becomes clean and crystal-like sparkling. Follow the formula given below to add the shock quantity.
(Total chlorine – Free chlorine) x (Number of gallons/10,000) x 2 = amount of shock to add
When you add the shock to your swimming pool, let it rest for a 3, 4 hours. Now test the chlorine.
If the problem exists, add some more shock.