SLAM ?successful, but CC still high at times

GeoQuack

Active member
Sep 4, 2016
29
Melbourne, Australia
I had to slam my pool for the first time. The clockwork timer stopped working, combined with a couple of big storms, lots of rain and leaves all over a cover with the water from this mess going into the pool... Pool never went green but did get cloudy. I now have lovely clear water, but CC is between 0.5 and 2 still. I do get quite a few leaves and the occasional bird or possum poo in the pool and I'm wondering whether I'm finished and the test is wrong or there's some other source of CC or do I still need to continue the SLAM?

SLAM started 12 days ago
Tests before SLAM:
FC 1, CC 0.5, pH 7.2, TA 80, CYA 80, TH 370, Borate 30, Salt 3500

For the first 36 hours added lots of liquid chlorine and ran SWG at 100%. Pool very clear at 24 hours, beautifully clear at 48. By 48 hours got SWG run away with FC 40. Now have to manually turn SWG off and on as chlorine is still going up with it set at 25% (lowest setting) with the pump running 24 hours/day.

Have done OCLT with a result of 1 both times.

I have an oversized single speed pump and this is costing a fortune in electricity. Do you think I can stop and the CC is coming from leaves, etc, or is there something still growing in the pool?

Current test results are (day 12) FC 35 CC 1.5. (I have not done any others as I believe that the high FC will play havoc with the results.)

Thanks for your help,

Peter
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
969
Bunbury, WA, Australia
Hi Geoquack,
In a healthy pool, your CC's should be able to be kept relatively low most times but

A couple of things-


-if are SLAMing and you have CC's of >1 then you need to keep going but it would be best if you run the SLAM with the SWG off, simply relying on the liquid chlorine to maintain the correct level.
-Additionally, are you turning the SWG to run the OCLT as this will affect your result
-Have you removed the cover while conducting the SLAM? The cover will prevent the CC's from being burnt off by the sun if it is on the pool.
 

jimbowrench

Gold Supporter
LifeTime Supporter
Jun 22, 2015
14
Littleton, CO
G'day Geoquack,

As long as you have organic material in your pool, you will lose FC, and create CC. I am not sure you needed to SLAM based on your numbers prior to doing so. I would have raised the FC to shock level, removed the leaves, etc... and given it some time to see where you were at with CC and clarity.
I have had experiences where in my absence for a day or two, I will return to find a dead toad, mouse, etc... in my skimmer, and cloudy water with elevated CC. I will add bleach to raise to shock, and by morning, my CC will be at 0.5 or less, and the water will be clear.
As far as removing the cover, I would recommend that any time you elevate your FC levels beyond normal, you remove the cover to avoid degradation by chlorine.

Cheers, Jim
 

GeoQuack

Active member
Sep 4, 2016
29
Melbourne, Australia
Hi Geoquack,
In a healthy pool, your CC's should be able to be kept relatively low most times but

A couple of things-


-if are SLAMing and you have CC's of >1 then you need to keep going but it would be best if you run the SLAM with the SWG off, simply relying on the liquid chlorine to maintain the correct level.
-Additionally, are you turning the SWG to run the OCLT as this will affect your result
-Have you removed the cover while conducting the SLAM? The cover will prevent the CC's from being burnt off by the sun if it is on the pool.
Why should I have the SWG off, it is doing a nice job of keeping the FC at the SLAM level without any liquid chlorine?

Yes, SWG off for OCLT.

Yes, cover has been off since I discovered this problem. I think my FC of 40 would have destroyed it too.
 

GeoQuack

Active member
Sep 4, 2016
29
Melbourne, Australia
G'day Geoquack,

As long as you have organic material in your pool, you will lose FC, and create CC. I am not sure you needed to SLAM based on your numbers prior to doing so. I would have raised the FC to shock level, removed the leaves, etc... and given it some time to see where you were at with CC and clarity.
I have had experiences where in my absence for a day or two, I will return to find a dead toad, mouse, etc... in my skimmer, and cloudy water with elevated CC. I will add bleach to raise to shock, and by morning, my CC will be at 0.5 or less, and the water will be clear.
As far as removing the cover, I would recommend that any time you elevate your FC levels beyond normal, you remove the cover to avoid degradation by chlorine.

Cheers, Jim
I'm interested in you thoughts, but I think in retrospect seeing the chlorine demand being very high for the first 24 hours of the SLAM and then dropping right off from 36 to 48 hours says that there was something organic consuming an unusually large amount of chlorine, however, this has been gone for almost 12 days, but I'm still getting high CC levels, something that has rarely happened before, even with a storm and a lot of leaves and pollen. I wonder if the CC test get inaccurate at (very) high FC levels?

Yes, cover has been off the whole time.
 

pabeader

LifeTime Supporter
TFP Guide
May 14, 2015
4,349
Cartersville Ga
SWG off to save it's limited lifespan. Most SWG cells are good for a certain number of hours. During a SLAM you are using bleach or liquid chlorine to clean up your pool, why not give the SWG a break? Plus, if it's on all the time, then you can't tell if the FC use is tapering off.
 

jimbowrench

Gold Supporter
LifeTime Supporter
Jun 22, 2015
14
Littleton, CO
I assume you've cleaned/backwashed your filter.

I think it would make sense that at the elevated FC levels the chlorine would be way more aggressive towards leaves, pollen, and possum poo, creating elevated CCs. I guess it is back to, as long as there are organics in the water, you will consume FC and create CC.

I have to agree with running the SWG during the SLAM as it is efficient once you bring the FC to SLAM with liquid, and obviously turning it of for the OCLT.
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
969
Bunbury, WA, Australia
It is suggested to turn the SWG off to save the cell life. SWG's make chlorine slowly when a SLAM will often require regular and large doses best delivered by liquid chlorine or bleach. It also makes it easier to ascertain chlorine loss between doses without the SWG variable thrown into the mix.

How often are you currently testing for CC's?
 

GeoQuack

Active member
Sep 4, 2016
29
Melbourne, Australia
I have been absent for 9 days because my wife went into labour a bit early with our third child. All are safe and well, but I have been just a little distracted from looking after the pool...

I am very glad for the SWG which kept doing its job, even when I wasn't doing mine (for the pool at least). I have passed another OCLT (loss of 1), but CC remains around 1.5. Over the last couple of days I have turned off the SWG and my FC has been falling by 2 to 2.5 per day. I plan on keeping the FC at or just above my target level of 11 for my CYA of 80 for at least the next few weeks. Hopefully we will have some calmer weather and I get less organic matter entering the pool from the gum tree and I can work out whether my CC is from something nasty in the pool or is caused by all the rubbish from the tree that I get during bad weather, which we have had a lot of over the past couple of weeks.

I'm interested in your thoughts on this plan. I will let you know how I get on.

GQ
 

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