CYA and CH very high, time to drain?

aztodd

Active member
Apr 11, 2021
28
Phoenix, AZ
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool Core-35
I just got the tf100 testing kit and tested my pool water. My results are below as you can see basically nothing is where it should be, but notably cya and calcium hardness are very high.

Separately, but related, I purchased a core 35 saltwater chlorine generator and plans to install it once it arrives next week. I want to make sure my pool water is in good shape before installing it, so I bought the testing kit to check the water quality accurately, since I knew it was off.

Based on the results, it's looking like I should just do a full drain and refill, but I was hoping to get a weigh-in from the experts here.


==========================================
Meyer pool
------------------------------------------
Build Type: Plaster (Pebbletech)
Volume: 10000 gallons
------------------------------------------
Latest Test Result Summary:
FC: 4.0 (17 minutes ago)
pH: 8.2 (17 minutes ago)
TA: 360 (17 minutes ago)
CH: 1050 (17 minutes ago)
CYA: 200 (17 minutes ago)
==========================================
------------------------------------------
Test Results 04-19-2021 @ 05:57 PM
------------------------------------------
Free Chlorine: 4.0
pH: 8.2
Total Alkalinity: 360
Calcium Hardness: 1050
CYA: 200
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
39,441
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Based on the results, it's looking like I should just do a full drain and refill, but I was hoping to get a weigh-in from the experts here.
I agree. Do it soon as the weather is only going to get warmer.
 
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aztodd

Active member
Apr 11, 2021
28
Phoenix, AZ
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool Core-35
Hello!

I am doing a full drain and refill this weekend due to very high CH (1000+) and CYA (200) levels.

I've gone through the pool school pages and searched the forum, but I don't feel that I'm finding a definitive answer for exactly what chemicals to add, and the timing after refilling. If I totally missed something please set me straight and point me in the right direction though. I had expected to see this as a stand-alone article in pool school.

What I think is accurate is the following:
  • Use liquid chlorine/bleach to chlorinate the pool
  • Add granular CYA vs liquid
  • Balance PH after pool chlorine is at the appropriate level, and stable (though I also see on the SLAM instructions it says to do PH first... so not sure on the order here)
My questions though are as follows:
  • When do I start adding these chemicals? Do I wait until the water is completely refilled?
  • Do I need to add CYA before the chlorine?
  • What is the best method for adding the CYA? Sock method? How long does it take to dissolve and distribute?
  • How should the chlorine be added? How much, how often? Do I need to SLAM the pool to get it started back up?
  • I assume I am running the pump 24/7 at first, but at what speed (I have variable speed Hayward pump) and then for how many days?
Thank you in advance for your patience, and help.
 
Last edited:

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
39,441
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
When do I start adding these chemicals? Do I wait until the water is completely refilled?
Sure. You need the pool pump running to distribute the chemicals. Also, test your water once it is full and circulated.
Do I need to add CYA before the chlorine?
Add 3 ppm of chlorine. Add enough stabilizer to get to 40 ppm CYA level using the sock method. Follow FC/CYA Chart
What is the best method for adding the CYA? Sock method? How long does it take to dissolve and distribute?
Use the Sock method. If you squeeze the sock, it will take an hour or so to dissolve. If you leave the sock alone, a couple days.
How should the chlorine be added? How much, how often? Do I need to SLAM the pool to get it started back up?
Pour the liquid chlorine needed in a small stream at a return jet with the pump running.
Daily.
No need to SLAM unless you have active algae right now.
I assume I am running the pump 24/7 at first, but at what speed (I have variable speed Hayward pump) and then for how many days?
No reason to run 24/7 unless you want to. RPM depends on what it takes to skim your pool surface. Start at 1200 rpm and see how that does. Since you will be adding liquid chlorine every day, just be sure the pump runs for 30 minutes or so after adding. Run time can be as little as 4-6 hours (see if that works to keep the pool clean) or up to 24 hours per day. With a VS pump, at low rpm, they typically use less than 200 watts per hour.

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aztodd

Active member
Apr 11, 2021
28
Phoenix, AZ
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool Core-35
No need to SLAM unless you have active algae right now.
I do have a minor amount of active algae right now, not enough to turn the pool green, but if I don't brush it every few days it starts building up visibly on some of the walls. Up until now I've just used chlorine tabs and shock to "take care" of the problem, but recently have been enlightened through this site about why that never was really solving the problem, and why I could never keep my chlorine levels stable at a reasonable level.

Should I consider SLAMing the pool to make sure all the algae is killed then after refilling?
 

aztodd

Active member
Apr 11, 2021
28
Phoenix, AZ
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool Core-35
Also - regarding the PH - should I balance that before or after chlorinating the pool?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
39,441
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Also - regarding the PH - should I balance that before or after chlorinating the pool?
The CYA is a bit acidic so it will drop the pH. Check the pH after a couple days.
 
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march2012

LifeTime Supporter
Jan 21, 2012
468
TX
Hello!

I am doing a full drain and refill this weekend due to very high CH (1000+) and CYA (200) levels.

I've gone through the pool school pages and searched the forum, but I don't feel that I'm finding a definitive answer for exactly what chemicals to add, and the timing after refilling. If I totally missed something please set me straight and point me in the right direction though. I had expected to see this as a stand-alone article in pool school.

What I think is accurate is the following:
  • Use liquid chlorine/bleach to chlorinate the pool
  • Add granular CYA vs liquid
  • Balance PH after pool chlorine is at the appropriate level, and stable (though I also see on the SLAM instructions it says to do PH first... so not sure on the order here)
My questions though are as follows:
  • When do I start adding these chemicals? Do I wait until the water is completely refilled?
  • Do I need to add CYA before the chlorine?
  • What is the best method for adding the CYA? Sock method? How long does it take to dissolve and distribute?
  • How should the chlorine be added? How much, how often? Do I need to SLAM the pool to get it started back up?
  • I assume I am running the pump 24/7 at first, but at what speed (I have variable speed Hayward pump) and then for how many days?
Thank you in advance for your patience, and help.
You likely dont need to do a full drain. Why not drain to about 25%, then refill. Then your CYA should be about 50 and there is no need to add more.

One thing I plan to do to combat CH is to have a gutter flowing into the pool to fill the pool with rainwater. It will actually cause the pool to overflow and remove calcium and CYA.
 
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aztodd

Active member
Apr 11, 2021
28
Phoenix, AZ
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool Core-35
You likely dont need to do a full drain. Why not drain to about 25%, then refill. Then your CYA should be about 50 and there is no need to add more.

One thing I plan to do to combat CH is to have a gutter flowing into the pool to fill the pool with rainwater. It will actually cause the pool to overflow and remove calcium and CYA.
I live in Arizona, what is rainwater? 🤣

Good idea though for places where it does rain somewhat regularly!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
39,441
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
How do I avoid CH rising so high going forward? Is this mainly just an unavoidable byproduct of having hard tap water?
The most practical way is to use softened water for your make up water due to evaporation. Do you have a whole house water softener?

Another way to at least slow it down is to use a cheap bubble cover over the pool, especially in the spring (April to late May) and fall (September to late October). During those times, your pool water temperature can easily be higher than the over night low temperatures. Evaporation can be very high during those times.
 
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