CYA and FC usage

[Ravenfan1969]

I had been having some trouble with FC losses of 3.5 to 5.5 ppm a day. My pool is in full sun from 10 am to 5 pm. My reading on my CYA test appeared to be between 40 and 50 then. After posting my issues I decided to add a bit more stabilizer a few weeks ago. I now am seeing 2 to 3 ppm drop per day. I tested my CYA this morning and it is between 60 and 70. I have trouble determining seeing the black dot lol. I have been targeting FC at 5 to 5.5. Should I be upping my FC even though I am having no troubles?

This mornings readings
FC 2.2
CC 0
PH 7.6
TA 90
CYA 60 to 70

 

[JasonLion]

Your FC level is too low. With CYA at 60 to 70 you want FC to be between 5 and 10 and never below 5.

It is difficult to tell for sure, but one possible cause of excess chlorine consumption is a low level algae problem. I recommend doing an overnight FC loss test to verify that there isn't anything using up chlorine other than sunlight.

 

[Ravenfan1969]

My over night FC loss is between .5 and 1 ppm

 

[JasonLion]

Then I guess that is normal for your CYA level.

You might want to read over the Notes section in this post about how to do the CYA test.

 

[cardano]

One other suggestion since your CYA level is getting to the point where this help - is to run the test at half strength and see what result that gives you. Jason says to only do that at 90 or above, but it helped me isolate my CYA level and I'm down at 60(ish).
From
CYA Extended directions
9. If your CYA level is 90 or higher, repeat the test adjusting the procedure as follows:
Fill the mixing bottle to the lower mark with pool water.
Continue filling the mixing bottle to the upper mark with tap water.
Shake briefly to mix.
Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark.
Continue the test normally from step 3, but multiply the final result by two.

 

[Ravenfan1969]

After trying the extended test it is reading about 65 to 70 on the CYA. Should I try to drop down some or just keep going as I am. My overnight drop was 1.0 and with a partly cloudy day yesterday it only dropped 1.5. my average daily drop is about 3.0

 

[JasonLion]

Your daily FC loss is already on the high side. I would leave things as they are, rather than lower CYA.