Opening Numbers help please

[mickey4paws]

Just opened our pool yesterday. The water temp upon opening was 54 degrees, and after running heater, temp is now 74 degrees.

We have a vinyl lined 20k gallon inground pool and have a SWG. We have not turned on the SWG yet. We added 2 gallons of 10% liquid chlorine last night, which according to the pool cal, should have raised chlorine from 0 to 10.

Just ran a test:

FC 0.5
CC 1.0
TC 1.5
pH 7.3
TA 120

I didn't do the CYA test yet (will be doing tomorrow) and then I just bought some powder CYA which I'll be adding, but if I remember correctly, it takes a week or so for the numbers to increase.

The pool has had the solar cover on today, plus it was raining all day.

Is it normal for my FC to be so low after adding 2 gallons of chlorine? Husband says the chlorine must be defective :lol:

 

[jblizzle]

Well, clearly there must be something in the water consuming the FC. You need to test the CYA, dose for around 30ppm as required, follow the shock process (assuming the CYA is active even though it may take a week to show up on the test). Once the shock process is complete, then bump the CYA up for SWG levels and fire up the SWG.

 

[mickey4paws]

Thanks, Jason, I appreciate it. Yeah, never had this problem with an opening before so it kind of surprised me. Water is crystal clear, but yeah, there has to be something consuming the FC. Will shock and hope for the best

 

[jblizzle]

There is no "hoping" required. It WILL work

 

[mickey4paws]

UPDATE: Sorry I haven't posted back in a few days, my computer was down. Anyway, after 4 days of the shock process, I am happy to say that we passed the OCLT this morning. I still don't understand it. The whole time the pool was crystal clear, but CC was always 1 and chlorine would go from shock level down to zero overnight.

Here's this mornings number: FC 23, CC 0, CYA 60
Now I'm just wondering how long it will take for the FC to go down, then I will start the SWG. Thanks again!

 

[jblizzle]

Safe to swim up to shock level if that is a concern. You will likely lose at least 25% of the FC each day if you have a fair bit of sun.