Barack has expertise in pool chemistry and pool maintenance. He writes in-depth articles about how to maintain pools for optimal enjoyment.
Chloramine Disaster: Fighting Extremely Cloudy Pool Water with High CC Levels, Zero FC and Cyanuric Acid
You have Chlorine Lock when you add lots of chlorine in your pool water, but free chlorine(FC) level will not hold at 3ppm or higher, and drops drastically to zero or close to 0ppm within few minutes.
Chlorine Lock is known to be caused by a couple of issues, and one of them is very high Cyanuric acid levels that calls for high demand of free chlorine for the same effect, view Chlorine/Cya chart and know the ideal level of Cyanuric acid in relation to FC levels to avoid high demand for chlorine and cloudy water.
Before assuming any cause of extremely cloudy pool water, test and make sure that your Cyanuric acid level is within the range recommended for a standard pool, which is 40-80ppm for harsh chlorine based pools, and 60-80 for saltwater pools, and 20-30ppm for indoors pools, all with 3ppm free chlorine all the time.
The second and most common cause of milky pool water that won't clear up easily is presence of ammonia in a swimming pool. Unlike severe cloudy pool water caused by ammonia, mild cloudy swimming pool water is always associated with low free chlorine(FC) levels in water, but can be easily fixed by adding little liquid chlorine shock on a daily basis to keep chloramine under control, by killing bacteria and microorganisms in your water.
However, during summer opening, a lot of swimming pools have extremely high Combined Chlorine(CC) levels with next to zero or zero FC and Cyanuric acid, which in turn makes pool water extremely cloudy and very difficult to clear since a lot of chlorine is used, but very small to no change is seen in clearing the chloramine.
The main cause of chloramine disaster in a seasonal swimming pool that closes during winter and opens during summer is Ammonia. When you have ammonia in your pool, chlorine will be on a very high demand in your water but FC level will keep on dropping drastically and may not hold at recommended levels until you add sufficient amount of chlorine to eliminate ammonia.
Like I mentioned before, high Cyanuric acid levels in your water may also cause high chlorine demand, but you know it's ammonia when you add chlorine but your FC level doesn't hold and may fall rapidly to 0ppm, CC(chloramine) is very high, and Cyanuric acid levels is extremely low. Cyanuric acid level goes down because bacteria converts Cyanuric acid into ammonia, reducing its level sometimes to 0ppm.
Developing ammonia in an open and running pool is not easy when you constantly chlorinate your pool since Free Chlorine and Cyanuric acid will always be balanced, and bacteria causing ammonia will not thrive in your pool.
Ammonia begins to thrive in your pool when FC level goes extremely low for any reason, leaving high Cyanuric acid levels in your water that is converted to ammonia by bacteria.
As such, when closing your swimming pool for winter, make sure you properly balance your water and do all the necessary procedures for closing a swimming pool, so that you will not have ammonia and algae thriving in your pool when you open it during the summer.
Signs that you Have Ammonia in your Swimming Pool
1. Huge Drop in Cyanuric Acid Level
When your Cyanuric acid drastically drops down, sometimes to zero or close to 0ppm, that is a very strong indication of ammonia in your pool. Bacteria converts Cyanuric acid to ammonia, leaving your pool with less or no Cyanuric acid. As such, when your Cyanuric acid drops drastically, start by testing your water for ammonia in a nearby aquarium supply store.
2. Zero Free Chlorine Level
When your water has 0ppm FC or close to that and ideal FC level cannot hold after adding a lot of chlorine shock, your pool water might have been affected by ammonia and you will need a lot of liquid chlorine to eliminate ammonia, bacteria, and other microorganisms causing high CC levels.
3. High CC and Very Cloudy Pool water
Cloudy swimming pool water caused by ammonia will be extremely cloudy(milky) with high CC(Chloramine) levels and may need a lot of liquid chlorine to clear up. If you have been adding lots of chlorine in your pool but FC level is not rising or drops quickly after rising, you are dealing with ammonia and you need to clear it ASAP. Below is how you can get rid ammonia in your pool, and stabilize FC levels.
How to Eliminate Ammonia and Balance FC in your Swimming Pool
1. Drain and Refill with Fresh Water
Draining your pool water and refilling with fresh water is one the solutions for eliminating ammonia in your pool. If that seems a lot of work, you can get a Sump Pump and place it at the deep end, and have fresh water pumped in through the shallow end. This will reduce ammonia levels to manageable levels where you can add chlorine and eliminate it easily.
2. Use Sodium Hypochlorite Liquid Chlorine
If you choose to eliminate ammonia using chlorine, you can roll up your sleeves and start by finding yourself sodium hypochlorite liquid chlorine, and a lot of it. I recommend Sodium Hypochlorite chlorine shock because it doesn't deposit other pool chemicals in your water like other shocks including Calcium Hypochlorite, Dichlor or Chlorine tablets that affect pH, CH, and Cyanuric acid. Do not add more Cyanuric acid during this process since you will be feeding bacteria and creating more ammonia in your water.
Steps for Eliminating Ammonia Using Chlorine
1). Add Chloro Guard or HASA Sani-chlor 12.5% liquid chlorine in your water to raise FC to 10ppm. 10 ounces fluid parts should raise 10,000 gallons pool by 1ppm. Chloro Guard and HASA Sani-chlor are my immediate liquid chlorine options because they act faster and add no other chemicals in your water interfering with your water chemistry.
2). Take your FC reading after 15 minutes, if FC level does not hold between 5-10ppm, quickly add chlorine to raise FC to 10ppm and test again after 15 minutes.
3). Repeat the process until your FC holds between 5-10ppm to be sure your pool is finally free of ammonia and bacteria, don't panic if FC is stable but water is still cloudy, it will evetually clear up. However, if your are not seeing any rise in FC levels and water still cloudy after adding a lot of chlorine, that means you have a lot of ammonia in your water and chlorine is being consumed faster, and the best thing to do is to drain 1/2 to 1/3 of your pool water and refill with fresh water to lower levels of ammonia before adding more chlorine.
4). Finally when chlorine holds and water clears, balance your water chemicals starting with pH and TA, then Cyanuric acid and Calcium Hardness(CH).
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.