FC issues...Getting expensive

lindz18

Well-known member
May 9, 2015
397
TN
I am passing overnight, no CC, very clear water.

My pool is taking a gallon a day to keep my FC in range.

CYA is 50, pH 7.8 pushing 8, TA 60

I am having to pour a gallon a day and this is getting expensive, not to mention a pain having to buy it so often. Any ideas? Am I trying to keep my FC too high? For instance this eve it was 3.5 and I tried to get it to 6. Check FC at 15 mins and it was 8.5.
I have what is called a play pool where about 80% of my pool is 3.5 and the rest 6 foot. The best I could figure it was 24k gallons. Maybe I am figuring too many gallons in my pool.

Another question.... When it says target for CYA of 50 is 6-8, do you shoot for 6?
 

Oly

Gold Supporter
Jun 28, 2017
960
Fresno, CA
What % chlorine are you using?
It is possible some of your chlorine may not be the % you assume.
It also common to incorrectly estimate water volume.
You should be able to dial in your water volume my testing after application and adjusting your volume numbers.
I target the top of my range or slightly above as I expect a 2ppm drop in 24 hours.
If you get too far above your target range you will get more FC loss due to solar radiation.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
10,577
Evans, Georgia
Yup, Oly is right.... the sun is going to take its "tax" of 2-4ppm no matter what. So if your ideal range is 6-8, I personally aim for 9 or so so when I lose some I still will be over the bare minimum.

You have a large shallow pool....those UV rays just chew up your FC. Have you ever considered going for a SWG instead of bleach? The only negative to it is that you're paying for all your "bleach" ahead of time. But the price ends up being just about the same.

Maddie :flower:
 

lindz18

Well-known member
May 9, 2015
397
TN
Help me with the math to dial in my gallons...

My FC tested 3.5
I aimed for 6 and it told me 125 ozs.
I added 121 ozs. of 6% (19 120 code) (1 gal) and it tested out still 8.5 after 30 mins.

I forgot to add that my pool is 18x36



What % chlorine are you using?
It is possible some of your chlorine may not be the % you assume.
It also common to incorrectly estimate water volume.
You should be able to dial in your water volume my testing after application and adjusting your volume numbers.
I target the top of my range or slightly above as I expect a 2ppm drop in 24 hours.
If you get too far above your target range you will get more FC loss due to solar radiation.
 

lindz18

Well-known member
May 9, 2015
397
TN
I never thought about the shallow pool thing... Hmm!

Yup, Oly is right.... the sun is going to take its "tax" of 2-4ppm no matter what. So if your ideal range is 6-8, I personally aim for 9 or so so when I lose some I still will be over the bare minimum.

You have a large shallow pool....those UV rays just chew up your FC. Have you ever considered going for a SWG instead of bleach? The only negative to it is that you're paying for all your "bleach" ahead of time. But the price ends up being just about the same.

Maddie :flower:
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
10,577
Evans, Georgia
I get about 18,200 gallons for your pool as you've described it (3.5' for 80%, 6' otherwise)

That can explain why your FC went over after your bleach addition.

I also do think a very shallow pool can allow more "sun tax" to take effect. I hesitate to suggest you up your CYA level, cause that would also require you to up your FC base.....but sometimes that's what we tell folks out in the southwest or west to do.

Maddie :flower:
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
20,260
Laughlin, NV
Bleach might be stronger than 6%. Maddies volume gets you 3.2 ppm added with 121 oz of 6% bleach. If by chance it is 8.25% then the numbers work.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
10,577
Evans, Georgia
Well, I just used some Liquid Chlorine from Walmart and it was only 8 days since being produced. You know its got to be strong and fresh then! Perhaps you also had newly produced product.

As you add chemicals you'll be able to narrow down your pool's volume by seeing if you over or undershoot your goal.

Maddie :flower:
 

lindz18

Well-known member
May 9, 2015
397
TN
Still hard to keep my FC in....

Newest set of results:

FC 2.5
CC 0
CYA 40
pH is hard to tell... 7.8 - 8.0 (should I lower???)
TA 60
Water is tad cloudier than usual, but can see bottom, drain perfectly
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
20,260
Laughlin, NV
1 gallon of 6% bleach adds 2.4 ppm FC to your pool. That is on the low side. So 1 to 1.5 gallons per day is normal for your pool in the summer. If you cannot do that, then maintaining this pool will be problematic.
 

Donldson

TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
3,705
NW Ohio
Your water is "cloudier than usual"? Usual should be zero cloudy, any amount of cloudiness is cause for concern.

But other than that I agree with Marty, caring for a 24,000 gallon pool has a cost. TFPC may be cost effective, but keeping a large body of water clear and sanitary is not cheap.
 

lindz18

Well-known member
May 9, 2015
397
TN
1 gallon of 6% bleach adds 2.4 ppm FC to your pool. That is on the low side. So 1 to 1.5 gallons per day is normal for your pool in the summer. If you cannot do that, then maintaining this pool will be problematic.
Would you tinker with the ph or leave it alone?
 

lindz18

Well-known member
May 9, 2015
397
TN
Your water is "cloudier than usual"? Usual should be zero cloudy, any amount of cloudiness is cause for concern.

But other than that I agree with Marty, caring for a 24,000 gallon pool has a cost. TFPC may be cost effective, but keeping a large body of water clear and sanitary is not cheap.
Just a little. But zero cc and passing overnight
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
20,260
Laughlin, NV
I would suggest adding 20 ppm of TA using baking soda. When your pH is solidly an 8, lower it to 7.6. No lower.
 

Mackhatter

Gold Supporter
Apr 22, 2019
61
Washington State
Lindz, we have very similar pools. The only difference is that mine is indoors. I tried doing capacity calculations and came up with 24k. I used that number with Pool Math and kept overshooting my targets. I'm slowly reducing my capacity (I'm using 23k now and things are falling more in line.

I guess my point is that you can use Pool Math and gentle additions of chemicals to reverse engineer your capacity and lock everything in. With our shallower overall depts, I can imagine the sun going after your FC with a vengeance.

It just takes a little time and perseverance. You'll have yours dialed-in too.