SLAM-ing - Marathon or Sprint - Overnight FC Loss

[Lawmann]

I've been sitting in the back pew of the Church of TFP for a few years and just moved down to the front pew. Now, I want to make sure I'm singing out of the correct hymn book. (Eye rolls are OK from anyone not from Texas or the South )

Background: A few weeks ago, my pool was Army green -- something that the Creature from the Black Lagoon may not dive into. I'll skip the pool store experience, but after some improvement, I got my TF-100 and now feel somewhat empowered. I have been SLAM-ing for about 8 days, and thanks to the great resources in this forum, think I have been doing it somewhat correctly. My pool is now aqua (an improvement) but cloudy. It is clear down to about two feet. My CYA is 40 and my SLAM target is 16. I have been adding liquid chlorine -- 10.0% from WalMart, Pool Essentials brand, date code 5/6/2021. I use the PoolMath app for the amount of liquid chlorine to add. Pump is running 24/7 and filter pressure is good and stable. I have been adding liquid chlorine at the return jets, often walking around the pool to add it at other return jets. During the day, I know I've been fighting the Texas sun (in addition to any "non-sun matters"). My pool is in the sun about 75% of daylight hours. The process seems to be a see-saw process, but I'm patient. For FC testing, I use the FAS-DPD test. I love it, because it makes me feel like a scientist, especially when using ml.

Question 1, Loss of FC Overnight: I decided to do an OCLT to get a better handle on any non-sun issues. Yesterday, I tested FC and added my last dose of liquid chlorine at 6:45 pm. The sun was not on my pool. Then I tested the FC two hours later at 8:45 pm and it was exactly 16, my SLAM target. This morning at 7:00 am with no sun, I tested FC and it was 11.5, or an overnight loss of 4.5ppm. I know I still have leaves on the bottom at the deep end but I can't see the bottom. Days ago, I tried to gently scoop them out and was somewhat successful but not enough. Plus scooping, no matter how gentle, will stir up stuff. There are no signs of algae, either in the corners, on steps, or on the light as far as I can tell. I am thinking the leaves may be the problem and I need to get them out, no matter how much debris is stirred up. Does this sound correct or do you have any other recommendations?

I was also interested in how much my FC was decreasing during the day, knowing that it's a combination of sun and non-sun matters. Yesterday morning, I added my recommended amount of liquid chlorine (after which FC reached 15.5) and, without adding any more, simply re-tested FC every couple of hours. My FC dropped in amount of 3.0ppm, 2.0ppm, 1.5ppm, and 2.0ppm during the day. These numbers are probably meaningless since the sun was at work, but I'm including them for what it's worth.

Question 2, Time it Takes for Liquid Chlorine to Adequately Spread: This is a random question, but in my situation (30K gal pool, pump running) about how long does it take for liquid chlorine to adequately spread, i.e., so you can get a correct reading putting the graduated cylinder most anywhere along the edge of the pool. If the answer depends on quantity added, please assume 128 oz. are added. In TFP I have read to wait 30 minutes after your last addition of chemicals to test FC for an OCLT, so I'm wondering if 30 minutes is the standard. It seems a bit short to me.

Thank you in advance for your help. TFP is awesome!

Glenn

 

[mknauss]

I am thinking the leaves may be the problem and I need to get them out, no matter how much debris is stirred up.

Correct. You will not get a clear pool until the solid debris is removed. It is consuming chlorine.

about how long does it take for liquid chlorine to adequately spread, i.e., so you can get a correct reading putting the graduated cylinder most anywhere along the edge of the pool.

With decent circulation, 30 minutes. For an odd shaped pool with only one return, you need to brush the pool to do it that quickly.

 

[phonedave]

Anything organic in your pool is going to consume CL. That is sort of the whole purpose of an OCLT. The chlorine does not care if it is an algae cell, a bacteria, a deal leaf, or an old ham sandwich. If it is in your pool and organic based, it is going to use up chlorine.

You can try vacuuming to waste to get rid of some of the larger stuff. You could also put in some skimmer socks if you are using a suction side cleaner. Just watch them, because if you do have a lot of gunk they will plug up pretty quickly (which is good, you want them to catch all the garbage). I have 10 or so skimmer socks. When I open, I just keep changing them as they clog, and then I rinse them all out at once. Some people use hairnets and then throw them away, but I try to do the reduce, reuse, recycle environmental thing, so I buy study ones, and hose them off.

 

[HermanTX]

I am thinking the leaves may be the problem and I need to get them out, no matter how much debris is stirred up. Does this sound correct or do you have any other recommendations?

As part of the SLAM process you should vacuum. Can you vacuum up the leaves? Preferably vacuum to waste but if you have to go to the filter that is fine. You may need to backwash or clean the filter ever so often.

In TFP I have read to wait 30 minutes after your last addition of chemicals to test FC for an OCLT, so I'm wondering if 30 minutes is the standard. It seems a bit short to me.

LC disperses quite efficiently. I think the technical term is hydrophilic meaning "having harmony with water".
Brushing helps as well but putting it in at different return jets is a good practice. 30 mins should be good.

FC was decreasing during the day, knowing that it's a combination of sun and non-sun matters.

It not uncommon to lose 2-4ppm (i.e. parts per million) of FC due to UV during the day. That is why you need to test every so often during the day because of both UV loss and algae loss on your FC level.

 

[Lawmann]

Correct. You will not get a clear pool until the solid debris is removed. It is consuming chlorine.

With decent circulation, 30 minutes. For an odd shaped pool with only one return, you need to brush the pool to do it that quickly.

Thank you, Marty. I'm on to removing the debris.

 

[Lawmann]

Anything organic in your pool is going to consume CL. That is sort of the whole purpose of an OCLT. The chlorine does not care if it is an algae cell, a bacteria, a deal leaf, or an old ham sandwich. If it is in your pool and organic based, it is going to use up chlorine.

You can try vacuuming to waste to get rid of some of the larger stuff. You could also put in some skimmer socks if you are using a suction side cleaner. Just watch them, because if you do have a lot of gunk they will plug up pretty quickly (which is good, you want them to catch all the garbage). I have 10 or so skimmer socks. When I open, I just keep changing them as they clog, and then I rinse them all out at once. Some people use hairnets and then throw them away, but I try to do the reduce, reuse, recycle environmental thing, so I buy study ones, and hose them off.

Thank you, phonedave. I just got some skimmer socks to help with the smaller stuff and hopefully reduce the number of backwashes. Appreciate the tip.

 

[Lawmann]

As part of the SLAM process you should vacuum. Can you vacuum up the leaves? Preferably vacuum to waste but if you have to go to the filter that is fine. You may need to backwash or clean the filter ever so often.


LC disperses quite efficiently. I think the technical term is hydrophilic meaning "having harmony with water".
Brushing helps as well but putting it in at different return jets is a good practice. 30 mins should be good.


It not uncommon to lose 2-4ppm (i.e. parts per million) of FC due to UV during the day. That is why you need to test every so often during the day because of both UV loss and algae loss on your FC level.

First, thank you for the correct technical term "hydrophilic". I am going to try to scoop up the leaves and then vacuum. I've been saving the leaves and vacuuming until now, and it turns out, the organic stuff is the remaining hurdle. I have testing several times during the day, but yesterday, I did just two tests to see what was happening to the FC level during the day. Looking back, not a very scientific experiment, since FC was being lost both to UV and algae. And thanks for setting me straight on "ppm". I have corrected "ml" to "ppm" in my original post to keep from confusing anyone.

 

[MITBeta]

There's no point in doing the ONCL test until your pool is clear.

 

[Lawmann]

There's no point in doing the ONCL test until your pool is clear.

Thank you.

 

[Bperry]

I've been sitting in the back pew of the Church of TFP for a few years and just moved down to the front pew. Now, I want to make sure I'm singing out of the correct hymn book. (Eye rolls are OK from anyone not from Texas or the South )

Background: A few weeks ago, my pool was Army green -- something that the Creature from the Black Lagoon may not dive into. I'll skip the pool store experience, but after some improvement, I got my TF-100 and now feel somewhat empowered. I have been SLAM-ing for about 8 days, and thanks to the great resources in this forum, think I have been doing it somewhat correctly. My pool is now aqua (an improvement) but cloudy. It is clear down to about two feet. My CYA is 40 and my SLAM target is 16. I have been adding liquid chlorine -- 10.0% from WalMart, Pool Essentials brand, date code 5/6/2021. I use the PoolMath app for the amount of liquid chlorine to add. Pump is running 24/7 and filter pressure is good and stable. I have been adding liquid chlorine at the return jets, often walking around the pool to add it at other return jets. During the day, I know I've been fighting the Texas sun (in addition to any "non-sun matters"). My pool is in the sun about 75% of daylight hours. The process seems to be a see-saw process, but I'm patient. For FC testing, I use the FAS-DPD test. I love it, because it makes me feel like a scientist, especially when using ml.

Question 1, Loss of FC Overnight: I decided to do an OCLT to get a better handle on any non-sun issues. Yesterday, I tested FC and added my last dose of liquid chlorine at 6:45 pm. The sun was not on my pool. Then I tested the FC two hours later at 8:45 pm and it was exactly 16, my SLAM target. This morning at 7:00 am with no sun, I tested FC and it was 11.5, or an overnight loss of 4.5ppm. I know I still have leaves on the bottom at the deep end but I can't see the bottom. Days ago, I tried to gently scoop them out and was somewhat successful but not enough. Plus scooping, no matter how gentle, will stir up stuff. There are no signs of algae, either in the corners, on steps, or on the light as far as I can tell. I am thinking the leaves may be the problem and I need to get them out, no matter how much debris is stirred up. Does this sound correct or do you have any other recommendations?

I was also interested in how much my FC was decreasing during the day, knowing that it's a combination of sun and non-sun matters. Yesterday morning, I added my recommended amount of liquid chlorine (after which FC reached 15.5) and, without adding any more, simply re-tested FC every couple of hours. My FC dropped in amount of 3.0ppm, 2.0ppm, 1.5ppm, and 2.0ppm during the day. These numbers are probably meaningless since the sun was at work, but I'm including them for what it's worth.

Question 2, Time it Takes for Liquid Chlorine to Adequately Spread: This is a random question, but in my situation (30K gal pool, pump running) about how long does it take for liquid chlorine to adequately spread, i.e., so you can get a correct reading putting the graduated cylinder most anywhere along the edge of the pool. If the answer depends on quantity added, please assume 128 oz. are added. In TFP I have read to wait 30 minutes after your last addition of chemicals to test FC for an OCLT, so I'm wondering if 30 minutes is the standard. It seems a bit short to me.

Thank you in advance for your help. TFP is awesome!

Glenn

I’d say you have a good understanding of the process and what your doing. Nice work, now get those leaves out.

 

[Lawmann]

I’d say you have a good understanding of the process and what your doing. Nice work, now get those leaves out.

I'll report back for sure. I learned everything so far from TFP, the website and forum posts. I even found threads on how to decipher the date code on bottles of liquid chlorine! The people here are amazing and so helpful, and the website, by far, is one of the best organized, easiest to navigate, and most user friendly I've seen. The lack of advertisements sure helps and makes TFP worthy of support by members (hint, hint ...).