SLAM’ing - going through lots of liquid chlorine

Steelkilt

Active member
May 21, 2020
30
Groveland, MA
Pool Size
22500
Surface
Vinyl
Chlorine
Liquid Chlorine
Hey TFP!
There is so much knowledge here, thank you for providing a place to research and make pool maintenance accessible to the layman. New pool owner here - opened up the pool back first week of May.
test strips routinely showed no FC, despite shocking w/ the powder on three occasions using pool store recommended product. Came here, and determined my need to SLAM.
since starting my slam on Sunday 5/31, I think I’ve gone through 20 gals of 12.5 liquid chlorine. This morning I still had a FC loss of 7.5. Still dumping in 2 gallons of liquid chlorine daily. Could anything else be going on? Pumps running 24/7 all week. I did take the light well off 3 days ago only to find nasty gray stuff, algae? The water is absolutely crystal clear otherwise. Feeling frustrated 🙁
 

frustratedpoolmom

TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
12,253
Key West, FL
Hey TFP!
There is so much knowledge here, thank you for providing a place to research and make pool maintenance accessible to the layman. New pool owner here - opened up the pool back first week of May.
test strips routinely showed no FC, despite shocking w/ the powder on three occasions using pool store recommended product. Came here, and determined my need to SLAM.
since starting my slam on Sunday 5/31, I think I’ve gone through 20 gals of 12.5 liquid chlorine. This morning I still had a FC loss of 7.5. Still dumping in 2 gallons of liquid chlorine daily. Could anything else be going on? Pumps running 24/7 all week. I did take the light well off 3 days ago only to find nasty gray stuff, algae? The water is absolutely crystal clear otherwise. Feeling frustrated 🙁

Sounds like you could possibly have had an ammonia issue. Have you read anything about it?
Stabilizer/CYA can convert to ammonia over the winter. It creates a huge chlorine demand at start up.

Were you seeing high CCs during this SLAM? What is your FC/CC level now?

I buy an ammonia test kit from the pet store at the start of each season and test for ammonia in all of the inground pools I care for. Save's a lot of time knowing what I'm dealing with right off the bat.
 

Steelkilt

Active member
May 21, 2020
30
Groveland, MA
Pool Size
22500
Surface
Vinyl
Chlorine
Liquid Chlorine
I have only read re: ammonia in the past couple days looking to diagnose my problem. My CC’s are routinely 0.5 in the morning. My FC was 18 this morning at rising, so added 100oz. of 12.5 bleach to bring back up to slam level.
 

splashpad

Bronze Supporter
Aug 2, 2017
2,712
SE Kansas!
Hi Steelkit, welcome and glad you are in good place here!

Can you post a set of full test results? (did you happen to check PH before raising FC)?
PH is not accurate when FC is over 10, as it provides a false high reading.
 

frustratedpoolmom

TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
12,253
Key West, FL
I have only read re: ammonia in the past couple days looking to diagnose my problem. My CC’s are routinely 0.5 in the morning. My FC was 18 this morning at rising, so added 100oz. of 12.5 bleach to bring back up to slam level.

Are you only testing CCs in the morning?

So what I learned when tackling ammonia situations (probably in the hundreds at this point) is the CCs are very high and FC very low within one hour of using traditional SLAM methods. So for example, raise the FC up to slam level, wait an hour or so and test both and the CC will be extremely high. That is indicative of the ammonia presence (without an ammonia test to confirm).

For every 1ppm of Ammonia, it takes 10ppm of chlorine to oxidize it. That's a LOT of chlorine. If you know off the bat your ammonia level, you don't have to drag it out over a series of days, you can do it in one day and move past it.

I can't say for sure that's your issue but a high CC reading combined with a low FC reading while SLAMming usually indicates the presence of ammonia. Eventually if you continue to add the liquid chlorine up to slam level, the ammonia will gradually be consumed, eventually.
 

JJ_Tex

Gold Supporter
Bronze Supporter
Jul 17, 2019
2,486
Prosper, TX (DFW)
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
+1 on posting a full set of results.

I do see their pool math logs from a week ago show a CYA of 60. Wouldnt the presence of CYA rule out ammonia?
 

frustratedpoolmom

TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
12,253
Key West, FL
+1 on posting a full set of results.

I do see their pool math logs from a week ago show a CYA of 60. Wouldnt the presence of CYA rule out ammonia?
Not always. I've actually had pools have both. Makes eradicating it much more difficult because it requires a longer process and more chlorine.
 
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splashpad

Bronze Supporter
Aug 2, 2017
2,712
SE Kansas!
You can ignore the PH, with high FC, it's likely giving a false high result.

I'm curious after seeing the logs, are you having water exchanged/drained from the pool? The CYA should not be going down like that. Has each CYA test been in full light (not evening time or dim indoors lighting)?
 

Steelkilt

Active member
May 21, 2020
30
Groveland, MA
Pool Size
22500
Surface
Vinyl
Chlorine
Liquid Chlorine
That was only my second CYA test, and it seems a bit subjective. No water exchanges. The only draining has been from 3 back washes over the past week...roughly every other day
 
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splashpad

Bronze Supporter
Aug 2, 2017
2,712
SE Kansas!
Hey TFP!
There is so much knowledge here, thank you for providing a place to research and make pool maintenance accessible to the layman. New pool owner here - opened up the pool back first week of May.
test strips routinely showed no FC, despite shocking w/ the powder on three occasions using pool store recommended product. Came here, and determined my need to SLAM.
since starting my slam on Sunday 5/31, I think I’ve gone through 20 gals of 12.5 liquid chlorine. This morning I still had a FC loss of 7.5. Still dumping in 2 gallons of liquid chlorine daily. Could anything else be going on? Pumps running 24/7 all week. I did take the light well off 3 days ago only to find nasty gray stuff, algae? The water is absolutely crystal clear otherwise. Feeling frustrated 🙁
Going back to your original post, I'm leaning towards the liquid chlorine had to "burn off" (oxidize) the "shock powder" and you may have been on the brink of green w/algae, but got ahead of it.
I would suggest to clean any areas you can get to that water is "touching", lights, jets, returns, outlets, steps, etc. Make sure algae isn't hiding behind it's slime coating and the bleach can actively "attack" it!

:edit to add:
Since your water is clear, I would let the FC come down to 10 or less, and check the PH again, with higher TA, your PH may be too high for the chlorine to do it's full work :)
 

Steelkilt

Active member
May 21, 2020
30
Groveland, MA
Pool Size
22500
Surface
Vinyl
Chlorine
Liquid Chlorine
Going back to your original post, I'm leaning towards the liquid chlorine had to "burn off" (oxidize) the "shock powder" and you may have been on the brink of green w/algae, but got ahead of it.
I would suggest to clean any areas you can get to that water is "touching", lights, jets, returns, outlets, steps, etc. Make sure algae isn't hiding behind it's slime coating and the bleach can actively "attack" it!

:edit to add:
Since your water is clear, I would let the FC come down to 10 or less, and check the PH again, with higher TA, your PH may be too high for the chlorine to do it's full work :)
Thanks for your knowledge and reviewing my posts. Unless there are any other conclusive suggestions, I will follow your advice, and report back :)
 
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splashpad

Bronze Supporter
Aug 2, 2017
2,712
SE Kansas!
Thanks for your knowledge and reviewing my posts. Unless there are any other conclusive suggestions, I will follow your advice, and report back :)
You're welcome! Just a few years around the forums paying attention to what worked and what didn't! :D Lots of notes!

Once the FC is 10 or less, and you can verify your PH (and address it, if it does test "true" high), definitely get your FC back up :)
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,609
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
Still a good idea to check for hidden algae as splashpad recommended. :)
 

Steelkilt

Active member
May 21, 2020
30
Groveland, MA
Pool Size
22500
Surface
Vinyl
Chlorine
Liquid Chlorine
Still a good idea to check for hidden algae as splashpad recommended. :)
Absolutely. I found a bit of algae on the back of the weir door sponge/float. Soaked that in bleach, and gave the whole skimmer basket and assembly a scrub. The light well and the stair trim seems to have been the biggest offenders. I will give all those areas another scrub today.
 
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Steelkilt

Active member
May 21, 2020
30
Groveland, MA
Pool Size
22500
Surface
Vinyl
Chlorine
Liquid Chlorine
Morning,
Here’s my latest test results. Added no chlorine since previous posts and let it come down <10. pH looks ok, only TA is out of range. Thoughts? Should I see how chlorine holds the next day or so? Get it back up to SLAM level?

Latest Test Result Summary:
FC: 7.0 (24 minutes ago)
CC: 0.5 (24 minutes ago)
pH: 7.6 (24 minutes ago)
TA: 190 (24 minutes ago)
CH: 275 (24 minutes ago)
CYA: 50 (24 minutes ago)
===========================
 
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