No chlorine

[esto]

Can’t keep chlorine in my pool (saltwater/SWG) and what I’ve been reading says to SLAM to achieve breakpoint chlorination. Trying to determine how much 10% liquid chlorine I would need to add at once to achieve the 10x level. My CC reading at pool store most recently was .15 but I am waiting on an FAS-DPD test to do myself. Pool is 26,000 gallons. Any insight would be helpful as I am a new pool owner.

 

[Texas Splash]

Welcome to TFP! Much of what you are asking depends on your current CYA level. Can you provide an accurate CYA? What test kit are you using? That will determine which FC level you will need to achieve as noted on the FC/CYA Levels.

Also see -----> Pool Care Basics

 

[esto]

Welcome to TFP! Much of what you are asking depends on your current CYA level. Can you provide an accurate CYA? What test kit are you using? That will determine which FC level you will need to achieve as noted on the FC/CYA Levels.

Also see -----> Pool Care Basics

CYA is 70. Currently have Taylor K-2005 kit.

 

[esto]

CYA is 70. Currently have Taylor K-2005 kit.

 

[Texas Splash]

CYA is 70. Currently have Taylor K-2005 kit.

Then using the FC/CYA Levels we can see that you need to use liquid chlorine to achieve (and maintain) a SLAM level FC of "28". If you do that and follow the SLAM Process page to the letter you should do fine. Since you'll be using liquid chlorine to maintain that elevated FC level, you can turn the SWG off during the SLAM Process until you pass all 3 SLAM criteria. Good luck!

 

[esto]

Then using the FC/CYA Levels we can see that you need to use liquid chlorine to achieve (and maintain) a SLAM level FC of "28". If you do that and follow the SLAM Process page to the letter you should do fine. Since you'll be using liquid chlorine to maintain that elevated FC level, you can turn the SWG off during the SLAM Process until you pass all 3 SLAM criteria. Good luck!

Ok, I see where it is showing 28. With that being said how many gallons of the liquid chlorine am I required to add to achieve the 28? And once I get it there, if it drops to 14 after a few hours, do I increase it back up to 28? How long do I do this?

 

[Texas Splash]

With that being said how many gallons of the liquid chlorine am I required to add to achieve the 28? And once I get it there, if it drops to 14 after a few hours, do I increase it back up to 28? How long do I do this?

Great question. You can download the PoolMath APP, load your pool's profile info, then go to the "Effects of Adding" section. There you can select bleach (which is the same as liquid chlorine), the correct strength (%), and enter an amount to see what effect it will have. Below in my signature and at the bottom of this web page is also a link to the older TFP Poolmath webpage version which does the same thing.

From there you add the proper amount of chlorine and re-test as needed in an effort to maintain that elevated FC level. The rate of FC drop will depend on the condition of your water and amount of organics. Usually larger FC drops are expected early in the SLAM Process, but then it "should" start to settle and become more predictable throughout the day as the SLAM continues so you get into a good routine. Hope that helps.

 

[esto]

If I am to maintain a FC of 28 during the slam process by constantly adding chlorine, won’t my chlorine levels be way too high at the end of the process? Is there something I am missing here?

 

[Texas Splash]

If I am to maintain a FC of 28 during the slam process by constantly adding chlorine, won’t my chlorine levels be way too high at the end of the process? Is there something I am missing here?

With a CYA of 70, the water and pool/equipment are safe with an FC of 28 and below. The FC of 28 is an elevated ratio of chlorine-to-stabilizer which has been proven to kill algae yet still be safe for the pool while you continue to inspect, clean, sweep, etc. Once you pass all 3 SLAM criteria, then you will allow the FC to fall on its own back to the normal level range as noted on the FC/CYA Levels.

 

[esto]

Ok, that clarifies things. Thank you!

While I wait on my FAS-DPD test to arrive today, I took a water sample to the local pool store and below are results:

FC- .79
TC- 1.22
CC- .43
pH- 7.4
Alk- 170
Adj. Alk- 150
Calcium- 170
CYA- 70
Phosphates- 0
Salt- 3500

They told me to simply add 5.5 lbs of cal hypo after I told them I haven’t been able to keep chlorine in my pool. My SWG has also been running at 100% the last 2 days. When I brought up the SLAM process, no associate seemed to know much about it.
It seems like just doing their recommendation would be a waste.

Thoughts?

 

[Mdragger88]

If I am to maintain a FC of 28 during the slam process by constantly adding chlorine, won’t my chlorine levels be way too high at the end of the process? Is there something I am missing here?

It is safe for swimmers, equipment, & surfaces with fc anywhere between minimum & slam level for your cya so long as you can see the bottom of the pool for swimmer safety.
Once you have passed all 3 end of slam criteria you will then allow fc to fall to target range for your cya
FC/CYA Levels & set your swcg to maintain that level.
The fc level will fall to target range fairly quickly (within a few days) if you’re no longer adding any chlorine. The higher the fc the faster it falls.

 

[mknauss]

Be ware adding cal hypo if the SWCG is generating. You can scale it up really quick if pool water with a slug of calcium gets pulled through it.

 

[Mdragger88]

Ok, that clarifies things. Thank you!

While I wait on my FAS-DPD test to arrive today, I took a water sample to the local pool store and below are results:

FC- .79
TC- 1.22
CC- .43
pH- 7.4
Alk- 170
Adj. Alk- 150
Calcium- 170
CYA- 70
Phosphates- 0
Salt- 3500

They told me to simply add 5.5 lbs of cal hypo after I told them I haven’t been able to keep chlorine in my pool. My SWG has also been running at 100% the last 2 days. When I brought up the SLAM process, no associate seemed to know much about it.
It seems like just doing their recommendation would be a waste.

Thoughts?

I don’t know your pool volume or your pool surface type so it’s hard to know what exactly 5.5 lbs of cal hypo will do to your water or if you actually need calcium.
But large cal hypo additions can cause cloudiness so they are to be avoided if possible during the slam process.
It’s no surprise that they haven’t heard of it. They are simply taught to sell products.
Tfp does things differently than pool stores as you have probably already noticed.

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[djdonte]

Just do yourself a favor and dont listen to anything the pool store has to say. I'm sure the employee you spoke with means well, but they are there to sell you stuff. Nobody here wants to sell you anything. You could SLAM with cal hypo but it would get expensive fast among other problems with the calcium. LC has nothing but chlorine, water and tiny bit of salt. Its all you need. They dont know or care about the TFP method because you wont need their 60 dollar bottles of pool perfect anymore. Their test results are to be taken with a grain of salt as well.

To echo the other recommendations here, start buying as much LC as you can and start slamming. Turn off your SWG as its more for maintaining FC, not super chlorinating.

 

[esto]

I truly appreciate everyone’s comments! Looking at the extended forecast where I live, there’s a good chance for rain over the next several days. Do I SLAM knowing that or wait it out?

 

[djdonte]

I would still slam. Clouds mean less UV. Only UV and organic matter consume FC.

 

[duraleigh]

The rain will have virtually no affect on the SLAM unless it's a Frog Strangler!

Nevertheless, I would not start the SLAM until I had the FAS/DPD test in hand. The SLAM really can't be done well without it..

So, if you can delay the SLAM, simply put 5 ppm of FC into your pool until your FAS/DPD gets in your possession. Then begin the SLAM.

 

[Mdragger88]

I truly appreciate everyone’s comments! Looking at the extended forecast where I live, there’s a good chance for rain over the next several days. Do I SLAM knowing that or wait it out?

Slam on - rain or shine.
Obviously still be safe & not poking around in the pool with a metal pole in a lightning storm lol

 

[esto]

Does the FAS-DPD test only measure to 25ppm? If I am supposed to achieve FC of 28 during slam, how can I tell?

 

[mknauss]

FAS - DPD is accurate to 50 ppm FC. Above 20 ppm the error is a bit more, but not an issue for SLAM level FC's.