Measuring High Chlorine?

This is not uncommon at the end of the swimming season, or after “fixing” the water chemistry following a battle with low chlorine.

Is this a problem?

Whether this is a problem or not depends on a number of things as follows:

How high is the Free Chlorine?

According to the CDC, anything over 5 ppm of Free Chlorine is unsafe for recreational swimming, so with no plans to be swimming, you can reduce the output level and wait.

How / Why is it high?

As the season is ending, the bather load declines and temperatures drop. Both of these factors will reduce chlorine demand. Similarly, if you’ve vanquished algae, reduced phosphates, optimized pH and CYA, or otherwise “fixed” your water, you will experience a drop in chlorine demand as well.

What should I do?

This depends somewhat on how soon someone wants to swim. Certainly, you turn down the output level of the SCG or even turn it off temporarily.

With no swimmers, correct water chemistry and moderate sunshine, you might see your level drop by approximately 0.2-0.5 ppm per day. Of course, more sun, higher pH, or improper CYA will speed this up.

It is important to test your chlorine level very frequently while you are bringing the chlorine level down since the rate of decline, the level of ongoing demand, and the replacement rate of chlorine at the lower output setting are uncertain.

What if I don’t have that much time?

We’re sorry to hear this, but frankly, we will pass on answering. We can’t advise swimming at any level over 5 ppm and we are unfamiliar with the hows and whys of any chemical interventions.