Clarification of the term "Target level" in CYA/Cl charts.

[lalittle]

I've always wondered about the CYA/CL charts' use of the word "target." Is the "target' the level you "aim for" when you add chlorine -- i.e. the highest "non-shock" level you should use -- or is it the "average" level that you try to make your FC levels center around over time? I understand that ideal levels will vary from one pool to the next, but I'm just asking for clarification of the term as it is used in the charts.

Thanks,

Larry

 

[Smykowski]

I think you you view it as the "average" over time, but you're right, because of the buffer provided by the CYA, there's nothing harmful about going higher. My CYA is at 50, so my range is 4-8. I tend to add bleach at 7, and I "target" 10-11.

 

[JVTrain]

My understanding is that it's a target to shoot for in daily chlorination. Adding more than the target will net you a less efficient use of chlorine because you lose some chlorine to organics that may enter the pool such as dust, bugs, bird droppings, etc. but you also lose it to sunlight. You lose FC to sunlight as a percentage of total FC. For instance, if you have 10 FC and you lose on a particular day 30% of that to sunlight, you have lost 3 FC to just sun. However, if you only need to have 3-7 FC you'll lose only 30% of 7 FC if you raise it to that level. So instead of losing 3 FC at 10 FC you lose only 2.1 FC at 7 FC to sunlight. Over time it adds up and targeting too high is actually a waste of FC. The target is meant to bring FC up to a good level so you are always above the minimum after a full day of sun and normal use but be efficient in usage of chlorine.

That's my understanding after reading here at TFPC but perhaps I need more reading/refreshing.

 

[jblizzle]

I think jvtrain explained it well. The main key is to keep the FC above the minimum. The higher above it you go, the more you will lose to the sun.

 

[mickey4paws]

Thanks, JVTrain. I never knew that.

 

[lalittle]

For me, there's a balance between using chlorine efficiently and simply making less work for myself. Even though I use more chlorine when I raise the FC to 12 and let it drop to 9, 7, and 5.5 over the next three days, it saves me time and bother by not having to add Cl every day. This, to me, is worth the extra Cl that is lost due to using higher FC levels part of the time.

In other words, I sacrifice some Cl efficiency in favor of better TIME efficiency. It costs a bit more, but for me, the time/work it saves is worth it.

Larry