Combined Chlorine question

[Tjk1812]

Good day to all..I have a 17,000 gallon salt water, fiberglass pool. Here are todays tests results:
pH - 7.3
Ch - 2-4ppm
FC - .5 ppm
CC - 2.0 ppm
Cal Hard - 300ppm
TA - 110 ppm
cya - 50 ppm

My question is why does my combine chlorine remain high? I swim in the pool with no irritation and I shocked the pool last weekend with 3lbs of HTH shock hoping it would get my CC down to be equal or less than my FC. Is it possible my reagent is bad or am I simply doing something wrong? The water doesn't appear cloudy but I simply can't get the CC lower. I put my chlorine cell on a 3 day boost last week hoping to get the chlorine to release its bond and increase the FC and that did nothing. Any help would be greatly appreciated. Thanks.

Tom

 

[Donldson]

Well, you are allowing your FC to drop well below the minimum for your CYA, per the FC/CYA Levels, so something is building up in your water that is reacting to create CC. Sounds like you are taking some bad advice from elsewhere, your CC needs to be 0.5 or less, not just equal or less than your FC.

Bottom line is a 1-time shock is not the solution (and 3 pounds of HTH wouldn't have even done much anyway) and implementing the SLAM Process and seeing it to full completion is. Once you get everything cleared and your CC in check maintaining your FC above 2 ppm and never dropping below it is key. It may help to raise your CYA level to better protect your FC from the sun, but be sure to adjust your FC target as well.

 

[mknauss]

If you have had an extended period with your FC below minimum as per the FC/CYA Levels, I suspect you need to follow the SLAM Process

Do an Overnight Chlorine Loss Test tonight if you wish to confirm. Be sure the SWCG is off and add liquid chlorine to raise your FC to 10 ppm this evening. Then test FC in the am before the sun rises.

 

[Tjk1812]

Well, you are allowing your FC to drop well below the minimum for your CYA, per the FC/CYA Levels, so something is building up in your water that is reacting to create CC. Sounds like you are taking some bad advice from elsewhere, your CC needs to be 0.5 or less, not just equal or less than your FC.

Bottom line is a 1-time shock is not the solution (and 3 pounds of HTH wouldn't have even done much anyway) and implementing the SLAM Process and seeing it to full completion is. Once you get everything cleared and your CC in check maintaining your FC above 2 ppm and never dropping below it is key. It may help to raise your CYA level to better protect your FC from the sun, but be sure to adjust your FC target as well.

Well, you are allowing your FC to drop well below the minimum for your CYA, per the FC/CYA Levels, so something is building up in your water that is reacting to create CC. Sounds like you are taking some bad advice from elsewhere, your CC needs to be 0.5 or less, not just equal or less than your FC.

Bottom line is a 1-time shock is not the solution (and 3 pounds of HTH wouldn't have even done much anyway) and implementing the SLAM Process and seeing it to full completion is. Once you get everything cleared and your CC in check maintaining your FC above 2 ppm and never dropping below it is key. It may help to raise your CYA level to better protect your FC from the sun, but be sure to adjust your FC target as well.

Thank you for the response...I will read up on the SLAM and perform. I have heard about it, never have performed it. I hope it corrects the CC.

Tom

 

[Tjk1812]

If you have had an extended period with your FC below minimum as per the FC/CYA Levels, I suspect you need to follow the SLAM Process

Do an Overnight Chlorine Loss Test tonight if you wish to confirm. Be sure the SWCG is off and add liquid chlorine to raise your FC to 10 ppm this evening. Then test FC in the am before the sun rises.

Thank you for the advice, you are the second to mention the SLAM method. I'm not too familiar with it but will read up on it and perform. Thanks again.

Tom