CC challenges and CYA out of control

May 22, 2012
6
0
NW Chicago burbs
#1
30 days ago I started my pool on the BBB program (well pretty much). My first challenge was lowering T/A from 200 to current 120 via acid + aeration; that concern is getting under control.

I'm having difficulty shocking (liquid chlorine) and eliminating the remaining CC. It's been as high as 2-3 and is currently at 1.5. I've tried shocking 3 times and haven't completely finished still. For the last 20 days my CYA is increasing dramatically but I've stopped adding any CYA, trichlor, or dichlor type products. Maybe 5% water replaced with local source during that time too. Here's my exact logs related to CYA levels.

5/16 added 1.6lbs dichlor shock
5/17 CYA measured at 15ppm - added 2 Trichlor 3" tabs (before I knew the problems with dichlor/trichlor)
5/25 added 1.6lbs dichlor shock
5/26 added 1.75lbs CYA (thinking it was still probably low)
5/29 CYA at 35ppm
6/5 CYA at 45
6/15 CYA now at 60 (and using only unstabilized liquid chlorine since 5/26)

Tonight I will shock again but am unsure what level FC to hold at for CYA of 60 - pool calculator shows 18 in the bottom blue suggestion box, yet the Pool School chart shows 24 as a shock target.

As always thoughts and suggestions are welcome.
P.S. Talor K-1720 on it's way from Amato already so I can be absolute about future CYA levels.

currently -
FC 1.5 - 2
CC 1.5
PH 7.6
T/A 120
CH 200-250
CYA 60
 

linen

LifeTime Supporter
TFP Expert
Jul 30, 2010
8,649
0
48
Twin Cities, MN
#2
Bejay1 said:
Tonight I will shock again but am unsure what level FC to hold at for CYA of 60 - pool calculator shows 18 in the bottom blue suggestion box, yet the Pool School chart shows 24 as a shock target.
Pick either one and go with it. I tend to use the poolcalculator, but the poolschool chart is more aggressive.

Bejay1 said:
I've tried shocking 3 times and haven't completely finished still.
We consider shocking to be a process not an event. Have you reviewed the shocking process? http://www.troublefreepool.com/pool-school/shocking_your_pool
You need to keep the FC at your shock level till you pass all three criteria (also in my sig).

Definitely do not use anymore trichlor, dichlor, stabilizer (for now). You are slightly higher than you want to be, but you should be able to manage it.
 

BoDarville

LifeTime Supporter
TFP Expert
Jun 5, 2012
3,843
2
DFW, Texas
#3
Bejay1:

Welcome to TFP :wave:

There is a lag time between adding Stabilizer (CYA) and having it show up on your test. It can take about a week or so to fully register on a test.

I plugged in your additions of dichlor, trichlor, and solid stabilizer into the Pool Calculator. For a 10K gallon pool, these additions increased your CYA by 47.1 ppm. Since you measured your CYA at 15 ppm on 5/17 (the day after your first addition of dichlor), that first addition likely did not register entirely on your test. Your last addition of the 1.75 lbs of stabilizer on 5/26 was the largest dose and that is now fully appearing on your test. Since you started at around 15 ppm and since added 47.1 ppm, this results in 62.1 ppm. So your CYA test results of 60 ppm appear to be valid.

Recommend following linen's advice on shocking.
 
May 22, 2012
6
0
NW Chicago burbs
#4
Success! We'll Linen, the more aggressive pool school target of 24ppm FC did the trick. I shocked in the evening, it held, and CC was less than .5 in the end.

Bo, thanks for the math check. Never saw the bottom of pool calc where you could plug in chem volumes and estimate effects. Guess I got too anxious to adjust too quickly to fix all. Hopefully with normal water replacement CYA will drop during the season a bit.
 

Richard320

LifeTime Supporter
TFP Expert
Jan 6, 2010
20,322
1
San Dimas, CA (LA County)
#5
60 CYA is manageable, maybe even desirable if your pool is in full sun all day. It means your minimum FC level needs to be 5, which is the limit of the color block tester, but if you have the FAS-DPD test it's no big deal; you can test FC that way.