Higher than expected FC loss, but not ruling out degraded liquid chlorine

[Oscar G.]

Im pretty sure some of the liquid chlorine I have been using is degraded. I bought 4 gallons a Lowes that was stored in the outdoor garden center here in Gilbert Az. I've been using Pool Math to calculate the chlorine additions and I am having to add more than I would expect. My CYA was around 20 on the last test which I am trying to increase to 50.

My FC reading per FAS/DPD was 1ppm at 6pm today and I intended to add 78oz of 10% chlorine to raise my FC to 6ppm but went ahead and dumped in a little extra so it ended up being just over 80 oz. This was a different batch of chlorine purchased from Fry's supermarket that was shelved inside the store. I retested at 8pm and got a reading of 7.5ppm, so it does not appear that this batch was low.

Is it also possible the low CYA is contributing to FC loss? Also, how long should I be waiting after adding liquid chlorine to retest? I waited 2 hours this time and I'm not sure if the chlorine would have been well dispersed.

Thanks in advance for any insight!

 

[mknauss]

In Arizona, you should have a CYA of no less than 50 ppm.

You can test for liquid additions 30 minutes or so after adding, pump running.

 

[Oscar G.]

In Arizona, you should have a CYA of no less than 50 ppm.

Should I be aiming for higher than 50? I was shooting for 50 CYA based on TFP recommendation of 30 to 50.

Ok, thank you. I added dry CYA and am waiting 48hrs after it dissolved to retest

In Arizona, you should have a CYA of no less than 50 ppm.

You can test for liquid additions 30 minutes or so after adding, pump running.

 

[Oscar G.]

In Arizona, you should have a CYA of no less than 50 ppm.

You can test for liquid additions 30 minutes or so after adding, pump running.

Should I be aiming for higher than 50 CYA?

 

[IceShadow]

I would start at 50 and see how well the FC holds in the sun. You can always add more - removing it means draining a significant portion of the water.

 

[mknauss]

No. Not with a non-SWCG pool.

Test your CYA each month from May through September. It will degrade some with elevated water temperatures.