How to lower combined clorine level?

maintainpool

Well-known member
Apr 30, 2018
70
Orange County, NY
#1
We are using liquid chlorine. Our TF test kit reads 1ppm FC and 3.5ppm CC. PH is 7.2, Alk 130, CH 350, water temp 66. CYA view tube can be filled to the top and looking down inside the tube at waste level the black dot is still visible although a bit hazy.

Do we have any CYA?

How do we get CC under 0.5ppm? How much liquid chlorine?
 

kabutotx

Well-known member
May 17, 2016
205
Phoenix, AZ
#2
Get you FC up to around 10, especially at sunset. Higher CC says you either have algae or ammonia. You don't want to add any CYA if you have ammonia. You can buy an ammonia test kit at a fish store. If the pool was green or hazy, you might just have algae. If ammonia is negative you can add CYA to 30 and FC to 12 for SLAM until all 3 criteria are met.
 

funandsun

Bronze Supporter
Jun 12, 2017
764
Bloomington Indiana
#8
How is testing only 30 minutes after adding liquid chlorine going to be accurate? Doesn't it take like 8 to 12 hours of the filter running to turn the water over only once? 1hp pump with 25k gallons.
If it makes you feel better, I wait an hour, but not for a full cycle.

Try it out and see for yourself.

TFP is not going to tell you to do something knowing that it is going to fail or guide you in the wrong path. It just isn't going to happen.
 

maintainpool

Well-known member
Apr 30, 2018
70
Orange County, NY
#9
We still have some dirt, algae or whatever on and above the water line of the vinyl liner, does that need to be cleaned before starting the SLAM process? The water is too cold to jump in and scrub the walls from inside.

The first 4 nights after opening the pool we put in 3x gallons of 10% liquid chlorine, we have not had over 1ppm FC on our tests yet...we test usually 12 hours or so after adding the chlorine.
It just seems like a lot of chlorine being used and we still have 3.5ppm CC... Hence this chlorine method is getting expensive.
 

JamesW

TFP Expert
Mar 3, 2011
12,676
#10
If you're getting 3.5 CC, then you probably have ammonia. You need to SLAM to completion. It might take a lot of chlorine. It is what it is.

What was the CYA at closing?
 

maintainpool

Well-known member
Apr 30, 2018
70
Orange County, NY
#12
Thank you all, really helpful and supportive community here.

We don't have any prior water metrics, we moved in after previous owners had pool closed.

We are new pool owners, so lots of learning and reading we have been doing. Had to choose a chlorination method, no to Calhypo because our CH is already at upper limits, Dichlor adds CYA and gets costly, being that our current CYA readings seem low (the black dot is still visible but hazy in the CYA test tube filled to top), assuming our liquid chlorine additions are being used up quickly.
We just put 5 trichlor pucks in feeder until CYA goes higher. Yes we have dry stabilizer, but figured the trichlor tabs are multi functional at this time... chlorine plus CYA addition together.

Pool store confused us... Said no to liquid chlorine as daily use because it makes salt levels rise which make TDS go too high.

So we decided to try the TFP method from the onset of pool ownership.
 

domct203

Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 4, 2015
3,959
CT
#15
How long should the full SLAM process take?
This depends on too many variables to give a time frame.

We really need a good assessment of the pool, and haven’t yet seen a FC test result 15 mins after adding bleach. Dose the pool with bleach to 10ppm using Pool Math, check FC in 15 min or so and report back.

If the FC is less than 5ppm you are battling more than algae, if the FC is over 5ppm you are most likely only dealing with algae and can start the process.

A picture of the water, preferably to include a ladder or stairs for depth perception, will also help.

Have you removed the Trichlor pucks? If there is bacteria in the water they will convert the CYA from those tabs into more ammonia.

Any chlorine added to the pool will instantly react to the ammonia, eliminating both to a degree. It takes an overall FC addition of approximately 10X the ammonia level to eliminate the ammonia.
 

maintainpool

Well-known member
Apr 30, 2018
70
Orange County, NY
#16
Put in 3 gallons of 10%, after about 20 mins FC is 1, CC is 9.

Before doing this latest chlorine addition FC was 0.5 and CC was 4.5
CYA is around 20.

The water looks clear and you can see to the bottom of deep end...8 feet.

So we don't get it why our FC is so low but water looks good.
 

JamesW

TFP Expert
Mar 3, 2011
12,676
#19
Assuming low CYA, target about 15 ppm fc.

If you add CYA, begin to maintain fc at about 40% of the CYA.

The two main things that cause such high CC levels are ammonia or sulfamic acid.

Sulfamic acid is used in some copper stain removers. Unless you have a reason to think that copper stain remover was used, it's an unlikely cause of the CC.

Since you're a tabs pool, the CYA was probably high at closing. Since there is none now, it's most likely that bacteria ate the CYA and converted it into ammonia.

The bacteria should be gone now, so you can begin adding CYA.

Test every few hours and add fc back to 15 ppm or 40% of the CYA, whichever is higher.