Going crazy - new owner with high CC

[gannoc]

Short summary: New house, first time pool owner. 25,000 gallon in-ground pool. When I opened the cover last month, it was green and full of leaves. Weeks of many shockings, DE backwashing, more shocking, etc, and the pool is clear, but I'm still struggling with chlorine.

I hadn't been checking the numbers daily. (beginners mistake), but I went to the pool store last week where I was told I had 0 chlorine and a ph of 7.0. I picked up a k-2006 test kit, added soda ash and almost immediately got an algae bloom.

More shocking later, and the water is clear. But now, no matter how much I shock, I get numbers similar to this:

FC - 0.6
CC -8.0
PH 7.4
TA 140
CH 280
CYA 55


When I went the pool store, they said my chlorine was fine, but I do not believe them unless the high CC can somehow interfere with the FC test. I did the test, my chemical engineer wife did the test, and we still get low chlorine and high CC every 24 hours after shocking.

BUT: I used a regular DPD test that the previous owners left behind, and the "FC Red" was higher than 3.0. What do I believe?

Calculators say I need to add 4100 oz of bleach to the pool. That seems completely insane to me. I don't even know how I would buy that without triggering some sort of bomb threat.

As a side note, it seemed to take 3x the amount of soda ash it should have to raise my pH, it that provides a clue to anything.

Any ideas? I suspect part of the problem is that I need to scrub the sides of my pool a little better.

 

[Bama Rambler]

If you're sure it isn't a testing error (and it seems you are), then it looks like you need to shock. First, lets define shocking to pool. It's not a 'throw something in one time' type thing. It requires that you put enough chlorine in your pool to bring it to shock level (17ppm for a CYA of 55) and testing and adding more an hour later and every hour until the FC holds.

If you wait 24 hours to test again then the FC gets all used up and whatever is consuming it grows at a faster rate so you're basically back to square 1.

According to the PC (pool calc) you need about 5 large jugs of bleach to get you to shock level. I'd go buy about 4 times that many or 20 jugs.

 

[gannoc]

Thanks! That makes sense. I wish I had just come here first and not wasted time and money at the pool store. Maybe I could have swam this weekend...

I've read in other places about "Chlorine Breakpoint" and they implied I'd have to get the pool up to 80ppm (10x the CC levels), and maintain that level order to clean the pool. I was ready to drain it and start over - I'm glad to find out I don't need to.

 

[JasonLion]

Yea, that whole breakpoint thing is more myth than fact. It may well still require a lot of chlorine, just not all at once.