Free Chlorine and Combined Chlorine

The basics of swimming pool maintenance.
New swimming pool owner's questions.
Help getting started with daily pool care.
sportsmom216

Free Chlorine and Combined Chlorine

Postby sportsmom216 » Mon 23 May, 2011 19:11

I have never owned or maintained a large pool before so I am a definite newbie. We inherited an in ground pool with the purchase of your new home. We have gotten rid of all of the algae and debris and we are presently getting ready to work in the chemical levels. One thing that I don't seem to understand is the difference between free chlorine and combined chlorine. I have a test kit but I think it only test for one...free chlorine I guess. Please explain them for me and and how to determine levels of both. Thanks!


chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Free Chlorine and Combined Chlorine

Postby chem geek » Mon 23 May, 2011 22:07

Free Chlorine (FC) is chlorine that can be made available to kill pathogens and oxidize bather waste. The actual level of active chlorine is roughly proportional to the FC/CYA ratio where CYA is Cyanuric Acid aka stabilizer or conditioner. Combined Chlorine (CC) is chlorine attached to ammonia and organics that is unavailable to disinfect or oxidize. It is rare to find CC in a proper managed outdoor residential pool.

Read much more including good test kit options at the Pool School .
sportsmom216

Free Chlorine and Combined Chlorine

Postby sportsmom216 » Tue 24 May, 2011 08:29

Thanks so much! I am not sure that I completely understand but I am beginning to get there. I may need to get a better test kit...not sure.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Free Chlorine and Combined Chlorine

Postby chem geek » Tue 24 May, 2011 10:46

Do yourself a favor and get either the Taylor K-2006 or the TFTestkits TF-100 with the latter kit having more volume of reagents you use the most and has very fast shipping and excellent service.

Return to “Basics for New Pool Owners”

Who is online at the Pool Help Forum

Users browsing this forum: No registered users and 9 guests