Low Free Chlorine

(FAC < 1ppm)

Cause Immediate Corrective Action Preventive Follow-up

High chlorine demand

Insufficient tablet delivery

Shock with Sustain Shock Treatment
Increase tablet delivery by one or more of the following actions:

  • If using adjustable skimmer dispenser lid, increase opening. If still insufficient, remove lid.
  • If skimmer space available, use additional tablet dispensers.
  • Increase circulation time. Increase water flow through skimmer by opening valve fully, decreasing flow through main drain.

Check Free Available Chlorine (FAC) daily and adjust tablet delivery from the skimmer dispensers to establish an FAC of between 1-3 ppm.

Low stabilizer level

Have your Authorized Sustain Dealer test your pool water's stabilizer level. If less than 30 ppm, increase to 30-50 ppm using chlorine stabilizer (cyanuric acid).

Check stabilizer (CYA) at least every 6 weeks.


What is the Difference Between Free, Combined, and Total Chlorine?

Take a minute now to brush up on your chlorine terminology. As a pool owner, it’s something you’ll need to know:

  • Free Chlorine is the chlorine in the water that is available to sanitize your pool. This is the chlorine you test for most often.
  • Combined Chlorine is the chlorine in your pool that’s already been used up while sanitizing your water. It still exists but has reduced ability to sanitize any further.  (Important Note:  When using the Sustain System, Shield is measured as “Combined Chlorine.”  So measured combined chlorine will actually let you how much Shield is in your water--Recommended dose is 1 ppm or greater).  
  • Total Chlorine is what you get when you add Free Chlorine and Combined Chlorine together.

Now that you understand the three types of chlorine, you can better understand how the Sustain 3-Part System works