CYA/Chlorine Correlation

alanrmeadows

LifeTime Supporter
May 5, 2010
137
I just retested my CYA this morning and is 50...which means I need to keep my chlorine level between 4 and 8. If I let my chlorine level fall to 1 or 2, is that the equivalent of letting it fall to 0 with little or no CYA? I guess what I'm wondering is there a danger for algae at the 1 or 2 level with 50 CYA or is the 4-8 level the ideal level and the goal is still to not let it get to 0.

Thanks,
Alan
17,500 Gallons
Fiberglass
Inground
Sand Filter
 

anonapersona

TFP Expert
LifeTime Supporter
Nov 5, 2008
2,598
You want to learn how much FC your pool typically uses in a day, and what it might use after heavy usage or a storm that brings in debris.

You want to add the amount that will certainly carry you through to your next testing plus some, and could take care of an adverse condition. So, a pool that usually consumes 2 ppm ought to be fine if you bump it up 4 ppm from the minimum. But if your dog swims a lot and that uses up 3.5 ppm a day, then you will need to consider going higher so that you have that wiggle room of not being surprised at a low FC number when you test.
 

alanrmeadows

LifeTime Supporter
May 5, 2010
137
Am I understanding this correctly...a FC level of 3 puts my pool at risk for algae? I definitely didn't know that.

Thanks,
Alan
 

gqjeff

LifeTime Supporter
Jul 19, 2010
203
IL
Alan, I never knew that either and the people at our local pool place do not either LOL. I think the FC level is 100% dependent on your CYA level... The higher the CYA the higher the FC has to be to sanitize.
 

svenpup

LifeTime Supporter
Nov 18, 2009
835
Sacramento, CA
gqjeff said:
Alan, I never knew that either and the people at our local pool place do not either LOL. I think the FC level is 100% dependent on your CYA level... The higher the CYA the higher the FC has to be to sanitize.
*ding* *ding* *ding* We have a winner! :goodjob:
 

alanrmeadows

LifeTime Supporter
May 5, 2010
137
Do most of you dose and test daily and try to get just above the minimum...or do you dose enough to get just above the maximum and let it fall to the minimum over a period of a couple of days?

Thanks,
Alan
 

alanrmeadows

LifeTime Supporter
May 5, 2010
137
Let me phrase my question this way...if my acceptable chlorine level is 4-8, is there anything wrong with increasing to 10 and letting it fall 3ppm per day until it reaches 4 after a couple of days?

Thanks,
Alan
 

svenpup

LifeTime Supporter
Nov 18, 2009
835
Sacramento, CA
alanrmeadows said:
Let me phrase my question this way...if my acceptable chlorine level is 4-8, is there anything wrong with increasing to 10 and letting it fall 3ppm per day until it reaches 4 after a couple of days?...
The only *slight* disadvantage to this is that FC loss to sunlight is proportional to FC level, meaning you will lose FC faster when it is higher.

So if you dose daily you might lose 2ppm per day, but if you try to double dose you might find you need to add 5 or 6ppm to ensure you stay above minimum instead of 4.
 

Other Threads of Interest