2013- A Summer of Extreme Sanitizer Demand-
Q: “How did I wind up with algae in my pool when my chlorine levels have been perfect!”
A: “Chlorine demand“ is a term service providers use to describe a pool’s specific sanitizer requirements. It is a term we must consider in extreme weather- chlorine demand is a concept that helps us prevent pool water going from clean to green- something that can occur in a very short time during extreme weather conditions.
As the term implies, sanitizer requirements will vary. We tend to adjust our sanitizer feeder equipment to “normal” and forget about it. The purpose of this post is to help you understand when “normal” sanitizer settings will not maintain sanitary water- under certain extreme conditions a pool’s sanitizer level can drop from “ideal” to zero in an hour.
So far, this summer has included some of the most difficult “chlorine demand” challenges I have ever seen. The following events are examples of things that can dramatically change chlorine demand; my goal is to help you recognize when something is happening and prevent problems:
- Hot weather
- Heavy rain
- Wash-in: Heavy rainfall shedding off lawns and gardens can contaminate pool water with organic matter and fertilizers.
- Heavy bather load- such as one might see at a holiday party that features swimming.
The Perfect Storm: This summer has included some long periods of hot weather: we have experienced frequent heavy thunderstorms with local torrential rainfall; add to all this a holiday party around the pool and the “normal” sanitizer levels are overwhelmed. Once sanitizer levels drop to zero a pool water is no longer sanitary for bathing- under these conditions water can cloud quickly and develop significant algae problems- often clouding within 24 hours. Pool Owners should also realize that pool water doesn’t cloud immediately once sanitizer hits “zero”- it is during this period that water- even though still clear, should be considered a potential health concern.
One fairly common health issue associated with swimming in pool water without proper levels of sanitizer is an ear infection- nicknamed “swimmers ear.” Such health issues are easily avoided if you understand extreme “chlorine demand” events and conditions and take precautions.
Recognize “Chlorine Demand” and Make Adjustments: Here are some things you can do to prevent losing the use of your pool for a week (or longer)- this is about the length of time it can take to recover and clean up from an algae outbreak or clouded water:
- Test water more frequently as chlorine demand conditions rise. You will “see” your sanitizer disappearing when you test and be able to make some good decisions before water clouds. You don’t have to be a certified water chemist to know the condition and quality of your pool water. Consider purchasing some good quality dip strips- this 5-second test is easy and gives you early warning to head off cloudy water and algae before it happens.
- Inform your service provider if you are planning a party. There are preventive things that can be done to handle the increase in bathers. It may be as simple as adjusting sanitizer feeder upwards and monitoring levels periodically. Normally a service provider comes weekly and balances the water and sanitizer levels. The point of this post is to help you recognize events or conditions that occur between visits that may be having a big impact on the water.
- Recognize when a heavy downpour may have introduced garden or lawn material into your pool- Fertilizer not only ties up pool sanitizer but at certain levels can render it ineffective! We will discuss how to remove Phosphates and Nitrates from pool water in another post; but you should be aware of any wash-ins and inform your service provider if this happens.
- Prevention is far easier- Preventing an outbreak of algae or clouded water is far easier and less costly than treating it. Clearing a cloudy pool or killing an algae bloom can be very expensive not to mention the disappointment of not being able to use the pool. Green water is probably the #1 or #2 reason why pool service providers are fired. The other reason being a slow response time. When sanitizer levels “crash” and water begins to cloud or algae has gained a foothold- time is critical.
In our upcoming blogs we’ll discuss some of the specific challenges presented by automatic pool covers and address bather issues such as sensitivity to chlorine or bromine.