Recovering a Pool that Got Out of Balance

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TT030

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Sep 15, 2012
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Massachusetts
I have lurked this site for a while and finally got fed up hearing about the conflicting advice my mother was getting from pool stores. Order the TF-100 and drove over to get some readings.

30,000 gallon vinyl pool.

Initial Readings
FC = 0
CC = didn't test
PH = 6.6
TA = 40
CYA = 80

The pool water is clear, but there are a few small spots of what appear to be black algae forming on some liner seams and there is some sporadic yellow staining on the liner and white stairs. I decided to bring the pool up to shock level and according to the pool calculator that is 21ppm given the CYA of 80. The bottles of bleach I'm using are 121oz @8.25% and the calculator called for 962oz (7.9 bottles). I just rounded up to 8. I should add that I brought the PH and TA levels back up 1st before I dealt with the chlorine levels.

I added the bleach at 11pm last night and didn't get around to retesting until 11am this morning and I am very surprised (and confused) with what I got for chlorine numbers. I ran the chlorine test a 2nd time to reconfirm these numbers.

FC = 2.5
CC = 9.0
PH = 7.5
TA = 100
CYA = 80 (carried over from 1st test)

Am I doing something wrong here? I added 968 ounces of 8.25% bleach and it didn't raise the FC number to the shock level of 21 that the pool calculator suggested it would. Is it normal to have that much burn-off overnight? I'm going to buy out Walmart's bleach supply at this rate since it is my understanding that I need to get up to shock level and maintain it there until that CC level comes down to zero.

P.S. Not sure if I posted this in the right spot so please bear with me if I didn't. ;)
 
This is exactly what I would expect. Your high FC level was consumed by organics in the pool, which raised CC level.

You are correct, you are going to need a lot of bleach to complete the process. Also, you need to brush off that black algae somehow, you can't just leave it stuck to the side of the pool.

I'll prepare you, you are going to see white/cloudy/milky water soon, if not already. This is the dead algae in the water. Keep an eye on pump pressures and backwash if needed.

While you are going through the shock process, ignore every test except FC and CC. TA, pH, CYA, can all be ignored, save your chems.
 
It is VERY common for your CC's to come up if you have organics in the pool.....your cc's took a BIG jump so you must have had a lot of junk in there....whether you could see it or not.

You may or may not get the cloudiness RobbieH suggest, but regardless, follow his advice and complete the shock process by keeping your chlorine up there constantly. The CC's will come down as the chlorine does it's work.
 
Just a quick update. Added 10 bottle of bleach last night which brought it up a little over shock level. FC dropped back down to 1.0 by 1pm today, but CC also dropped down to 1.0. 10 more bottles in tonight and we should be in pretty good shape in the morning. I had to cheat a little bu not keep it up at shock level during the day today due to a 4th of July party, but it is progress none the less.
 
Go ahead and put those bottles in today Russ and go get some more. At 1.0 PPM FC you are losing ground. Keep it up at shock level as best you possibly can until you are done with the process. Get it to shock level and maintain it there. ( This may be called the SLAM process before long) :) Stick around and you will find out for sure.

Welcome to TFP! :wave:
 
Added 10 more bottles last night around 10pm. As of 11am FC is back to 0 and CC is 1.0. Now I have a family friend over chirping that a CYA of 80 is low and should be between 100-120 and that is why it is "burning off so fast in the sun". He used to work at a pool store...
 
Keep your course. The idea that you WANT your CYA as high as 120 is crazy. Most will replace half the water when they get to 120 to bring it to 60 for a liquid chlorine pool.

Read the pool school about CYA. Trust the people here.
 
techguy said:
Keep your course. The idea that you WANT your CYA as high as 120 is crazy. Most will replace half the water when they get to 120 to bring it to 60 for a liquid chlorine pool.

Read the pool school about CYA. Trust the people here.
Click to expand...

Oh, I know where the level is supposed to be. At 80 it is already higher than I really want it. Figured I would just share this insight from a pool store guy that is sitting in my back yard while I work.. :roll:
 

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Ugh, went out to backwash the pool and ran into a new problem. Turned the pump off, set to backwash, and nothing happened when I turned it back on. After some troubleshooting it looks like the GFI next to the circuit panel in the basement has failed. 94 degrees with a FC reading of 0. Do not pass go, do not collect $200. Looks like I will be starting the shock process over from scratch once I get that swapped out and things back up and running..
 
Sorry to hear about your pump/gfi problem, let us know if you need help troubleshooting.

Russd3 said:
Now I have a family friend over chirping that a CYA of 80 is low and should be between 100-120 and that is why it is "burning off so fast in the sun". He used to work at a pool store...
Click to expand...
Actually, I would have suggest a partial drain/refill to lower cya down to 50 ppm as you first course of action before starting the shocking process.
 
linen said:
Sorry to hear about your pump/gfi problem, let us know if you need help troubleshooting.

Russd3 said:
Now I have a family friend over chirping that a CYA of 80 is low and should be between 100-120 and that is why it is "burning off so fast in the sun". He used to work at a pool store...
Click to expand...
Actually, I would have suggest a partial drain/refill to lower cya down to 50 ppm as you first course of action before starting the shocking process.
Click to expand...

It is on the high side at 80, but that would be a pretty significant drain/fill right at the peak of pool season. My mother was a heavy user of trichlor pucks through a chlorinator so that is obviously why the CYA is up their in the 1st place. Needless to say I informed her she is not allow to put anymore pucks in it for the time being. I suggested a partial drain/fill and she was not really on board with the idea when I brought it up. Maybe she will come around when she sees how much bleach I keep having her go buy. The water level is low on the skimmer so I have to add a few inches of water, but that will not result in much of a change.
 
Filter is back up and running after being out of commission for a little over 24hrs. I was out of town this morning so I didn't get any readings, but went ahead and instructed my mother to backwash and dump 8 bottles of bleach in once the electrician got the pool up and running. Much to her objection I threw a submersible pump in last night and pumped the pool just below the skimmer (it was already low from a lot of splash out from 2 large parties on the 3rd and 4th so most of that was already done for me). I don't have a gallon estimate, but I would say we added about 6 inches of water when all was said and done.

I got back around 5pm and grabbed a few quick readings. FC = 0.5 and CC = 1.0. Since some water was added I decided to do a quick spot check of the CYA level and came up with 65. It does make me think I might have been a little high with my initial reading of 80, but who knows. I ran the test twice this time and came up with 65 twice so I am comfortable with that number for now. The shock process is underway again after the brief hiccup with the electrical system so hopefully we are back on track.

Edit: 2 hours after adding 10 bottles of bleach and FC = 21 and CC = 0.5. Definitely lost a little in that 2 hour span since 8 bottles should be putting me up at 21. My alarm is set to check around sunrise to see how much we are losing. This has definitely been an experience and I think I need to buy stock in Clorox at the rate I'm going. Needless to say this is starting to get a little pricey and make we want to start investigating a salt system more and more.
 
Overnight loss test result time.

Dusk
FC = 21
CC = 0.5

Dawn
FC = 12.5
CC = 0.5

CYA = 65 (tested yesterday evening after 6" of water added to pool)

On a side note can an extremely high water temperature accelerate chlorine loss? The water temp is sitting at 86 degrees this morning from a thermometer that sits 2 feet below the surface. Needless to say the pool sits in the sun until 4pm this time of year.
 
Higher temps absolutely have an effect on FC solubility, but 86 F isn't an extreme high temperature. Even though it has an effect, you are losing more to the sun itself IMO. You are still losing a lot of FC overnight though, so keep hitting it and it will be over before too long. Good to see your CYA down a little. Maybe there was some test error, but don't worry, it's hard to be extremely precise with that one.
 
You might want to check a hardware store or even a pool store :shock: for liquid chlorine ...... i can get 5 gallons of 12.5 % for about $14 ....... which is roughly the same cost as 5 bottles of 8% bleach but will give you 50% more chlorine :mrgreen:

The 5 gallon jugs are not as convenient as individual gallon jugs but if you are dumping the whole thing in it may not be that big of a deal.
 
Russd3 said:
Overnight loss test result time.

Dusk
FC = 21
CC = 0.5

Dawn
FC = 12.5
CC = 0.5

CYA = 65 (tested yesterday evening after 6" of water added to pool)
Click to expand...

Progress finally! Brought it back up to shock level this morning (around 21) and tested it when I got home around dusk tonight. FC is sitting at 19.5 and CC is now at 0.
 

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