SLAM: First time SLAMing. Big FC overnight drop!

phappy

Well-known member
Aug 25, 2013
45
Hi everyone. I'm excited, as I've followed TPF for a long time but this is my first season where I'm doing all Liquid CL & following the TFP method. I opened the pool, and it was already quite clear.I have a FAS-DPD kit now. The FC was pretty much zero. I started the SLAM method.

My CYA is around 35.
So the Pool Math said the SLAM level to reach was 14.

I purchased a lot of 128oz 12.5% "Mega Shock" Diamond. I have used the Pool Math recommended amounts...and much more. And I still can't get to 14 FC! I got to 10 FC. I think maybe the percentage of 12.5% is actually degraded to much lower, but unfortunately the bottles don't have a manufactured date.

And now...the overnight FC drop test...went from 10 ppm FC down to 5 ppm!! (So now it's saying to add another approx. 2 gallons of 12.5%)

The water is crystal clear.

So, I guess my questions are:

1.) Do I keep putting in Liquid CL to get to the 14 ppm level (no matter how much CL I use)?
2.) Why type of increments should I add the CL? All at once?
3.) Do I have to keep the filter running 24 hours during the SLAM process? If I don't, and run it say 6 hours a day...what happens (regarding SLAM) vs. running it all day?

And this is exciting to learn...a bit frustrating, but I'm psyched to have finally committed to the TFP method. Thanks very much for your help & replies.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,976
Franklin, NC
1.) Do I keep putting in Liquid CL to get to the 14 ppm level (no matter how much CL I use)? Yes
2.) Why type of increments should I add the CL? All at once? All at once
3.) Do I have to keep the filter running 24 hours during the SLAM process? If I don't, and run it say 6 hours a day...what happens (regarding SLAM) vs. running it all day?24/7 until the SLAM is complete. If you have a localized area of algae growth with the pump off the water surrounding it will be depleted of chlorine. You want constant circulation so that if chlorine is depleted in one area eliminating organics it is replenished due to the circulation. The SLAM Process process has been designed to speed the elimination of all organics. Trust the process.
 

phappy

Well-known member
Aug 25, 2013
45
tim5055, thanks very much for the quick & helpful reply. I needed those answers for encouragement to keep on pressing on with the SLAM process. I'll now add the additional CL.

Thanks again!
 

phappy

Well-known member
Aug 25, 2013
45
Quick follow-up question: How soon after putting in the amount of liquid CL to get to the SLAM level (Pool Math recommended) should I wait to test the water again?'

Or...another way to ask this is, how long does it take for the CL that I put in to "register" in the water?
 

phappy

Well-known member
Aug 25, 2013
45
SLAM: Best to Get to FC Shock Target Quickly?

Hi all,

This season I've decided to do the TFP method, only liquid CL. I opened the pool seven days ago. I've been doing the SLAM method, and I'm learning along the way. My water is crystal clear and has been the entire time. There was no FC registering. I added a lot of liquid CL & have been using Pool Match exclusively.

But it has been hard to actually GET to the recommended 14 ppm FC level!

My question is: Is it best to quickly "overkill" on the amount of liquid CL, so you get the level up to and maybe even past the recommended shock level fast? It's been almost a week and I'm just now at the recommended shock level.

I'm running the filter 24hours, so it's costing a lot for electricity. So I thought why not put in more than needed chlorine immediately at the beginning of the SLAM process? It gets that FC to where you want it faster. And what is using more CL vs. paying for 24 hour electricity for filter?

Would this be okay to do? I'm trying to learn for next year. I'd rather not wait 7 days and counting to get the shock to it's recommended level. I'd like to actually swim in the pool soon! Thank you for your thoughts and replies.
 

phappy

Well-known member
Aug 25, 2013
45
Thank you domct203! I will fill out my signature. I don't have all that info in front of me. And thanks for combining the posts. (I didn't know if I should continue my other post or start a new one)

From the beginning, I added the recommended amount of 12.5% liq. CL, per Pool Math. But...I think that the Diamond Mega Shock that I bought may have already been very much degraded! It barely, and I mean barely, smells like bleach/chlorine. And when I tested, it was always off of the recommended 14ppm to shock.

So, is it acceptable to put in a lot of liquid CL so it goes beyond the recommended shock level? For example: If I put lots of "extra" liq. CL, and get the FC to 15 or 16 ppm. is that acceptable? (versus putting in measured amounts which don't seem to get me to my shock level easily).

Thanks again.
 

BattleOfYakima

TFP Guide
Apr 15, 2016
1,683
Central Florida
Try to avoid going over the shock level. PoolMath is a guide, usually a very awesome one! As you understand, the actual strength of the chemicals being added matters. Add what pool maths says to add, wait 30 mins, retest to see what actually happened, if you need more, plug the new results in PoolMath and add the new suggested amount. That's the technical answer.

The less technical answer is - if you have used half a bottle of a certain bleach/liqchor and are quite confident that the bottle is old/weak because testing resulted in less than expected - you could play with PoolMath lowering the & until you get roughly the predicted result to match what actually happened - or just round ... uhh that got wordy ... what I mean is - if that 12.5% isn't acting like 12.5%, pretend it is 10% when you use poolmath. If it doesn't act like 10%, make it 8.25% then if that fails 6%.

Do not use that technique for acid.

It is also possible to test the % of the liqchlor - search forum for test bleach strength and you'll find info on that, but why bother unless you're curious or going for a refund.

- - - Updated - - -

also, fyi, here is the date code thread, which, in conjunction with not buying bleach stored in the sun or excessive heat, will help you avoid these little bothers https://www.troublefreepool.com/threads/83147-Chlorine-Date-Code-Decoder-Easy-Way-to-Measure-Strength

 

phappy

Well-known member
Aug 25, 2013
45
BattleofYakima, thank you for your help. I just tested and the FC level is just at 14 ppm! And it only took a week! (Ugh. Now I know I should have "overkilled" it right from the start)

Now comes the part that makes me uncertain, as it's tough to know what amount to put in to "maintain" it at the 14 ppm shock level.

Thanks again friend!
 

BattleOfYakima

TFP Guide
Apr 15, 2016
1,683
Central Florida
know what FC was before add, how much you added, and then you retested and it was 14?

If so, we can use math:

After FC - (minus) Before FC = FC increase

FC increase / (divided by) oz (ounces added) = FC/oz of current bottle
 

phappy

Well-known member
Aug 25, 2013
45
(I added a signature!)

Man, this is frustrating. But I'm persisting!

- Last night the FC was at the shock target of 14 ppm Yeah!
- Filter has been on 24h a day
- This morning (tested at 11:30Am, pool has been in the sun already for a few hours), the FC dropped to 8 ppm! Boo!

This is the the EIGHTH day of SLAMMING ! The water has been crystal clear for the entirety of the SLAM process. I've been vacuuming & brushing.

I'm kind of at a loss now...Any suggestions guys?

jsptephens1, thanks for your idea about the volume of water. I was thinking about that. I calculated the water to be 26,730 gallons. It is an 18' x 36' pool.
 

BattleOfYakima

TFP Guide
Apr 15, 2016
1,683
Central Florida
Losing 6 FC in less than 12 hours is usually only due to any of the following:
1. algae/bacteria needing SLAMing and/or hidden algae
2. using magic potions from pool stores, especially sodium bromide products
3. user testing error
4. filter badly needing cleaning
5. CYA below 30

So, continue the SLAM, no doubt, but if any of those could be an issue, share your thoughts and let's investigate!
 

phappy

Well-known member
Aug 25, 2013
45
B.O.Y (Battle Of Yakima!), you have been so helpful with ideas & suggestions. Thank you so much.

So, I tool a water sample to my local pool store to test. They use a syringe to collect my sample and put it in a spinning cartridge type tester (I have know idea what it is called).

The pool store's test showed my water as:

CYA: 28 ! (I have to admit, in my Taylor K-2600 kit test for CYA I was never really satisfied with the black dot "disappearing". It really never quite did. So it is possible that the CYA is actually 28, vs. the 35 I was finding/estimating in my K-2600 test. How should I address?)

FC: 7.64 is what they say (My K-2600 test showed about 8 a few hours earlier, then I added two more gallons of "12.5" Diamond Mega Shock...pretty much proving that the shock I bough is completely degraded)

The pool store made a recommendation of perhaps trying Cal Hypo sticks. They claim it has no CYA. I will investigate this on TFP, but would you all have any ideas/suggestions about Cal Hypo?

Thanks again all.
 

Hammond

Bronze Supporter
Apr 23, 2017
61
Dallas, TX
If you aren't sure about the Diamond Mega Shock you could try plain liquid bleach. Make sure that it is unscented and that it is not the splashless kind. Lots of people,get the Walmart Great Value brand. They sell a lot of it, and it will likely be fresh.

You will I'll need more of it then the 12% that you have been using
 

GoGrabTheNet

Well-known member
Dec 13, 2015
76
Surprise, AZ
Question to the OP: Without going into the PoolMath calculator and trying to find out your pool size vs. the required shock value of 14ppm...is that a value to shock for green algae or mustard (aka yellow algae)? I ask because if you are battling yellow algae and a potential bloom of it, then perhaps your shock value is not high enough.

Was your pool green?

I need to research a little more myself on the various types of algae in pools, but I actually think that yellow algae may be more common, especially in warm-climate regions.

PS - Fill out a signature and your location in your profile. It really does help in troubleshooting! ;)
 

BattleOfYakima

TFP Guide
Apr 15, 2016
1,683
Central Florida
If you aren't sure about the Diamond Mega Shock you could try plain liquid bleach. Make sure that it is unscented and that it is not the splashless kind. Lots of people,get the Walmart Great Value brand. They sell a lot of it, and it will likely be fresh.

You will I'll need more of it then the 12% that you have been using
Unless the 12% you've been using has degraded below the 8.25% of the GV! :cool:

Cal hypo does not add CYA, see https://www.troublefreepool.com/content/142-how-to-chlorinate-your-pool. Since it does add CH, you have to use PoolMath and make sure you have the CSI room to add more CH without risking scaling. Also, I believe it is usually more expensive per FC added, there are threads and comparisons and calculators on this if you wish to search for them/if you care. I don't use it since I'm already at perfect CH and neutral CSI. No desire to mess with it in my case. Who knows, maybe you need CH or have CH room to play and maybe it is even cheaper. All up to you. You can ask any questions you have.

Did they do the CYA test with the little pill/pellet or drops? Oh wait, I don't really care. Not like they mixed for 30s and then let sit for 30s and then mixed again. Not like they went in sunlight.

Anyway, so your pool is losing a lot of FC. FC goes to sun and algae. Sun can't steal it at night. Do an Overnight Chlorine Loss Test if you want to get a better idea how much of your FC loss is to algae vs sunlight.

CYA can be a tad tricky. You really only want about 30-40 in most locations, but in super sunny areas, sometimes higher is more helpful than harmful. Based on your signature and profile, I see you live in ____:confused:______. I assume that is an average sunny place and 30-40 is fine. If you don't live in an average sunny place, then mention it. You don't have to share where, but it would help to know if you're in a brutally hot surface of the sun place or an eh sun isn't really even annoying here place. Ya know? Up to you.

Either way, your cya is 30 or 40, which gives you basic protection and you can certainly SLAM with that if you wish to. If you want to add CYA, use PoolMath and only add 5 CYA's worth at a time, testing 2 days apart until you either have theoretically added enough to be at 40 or your testing is definitively over 30. Either way, you'll round up so you'll use the 40 line of [FC/CYA][/FC/CYA].
 

wfrobinette

Member
Jul 5, 2017
23
POMPTON PLAINS
The pool store likely has old bleach because they push pucks and other granular shock

Use
Lowes and Walmart have 10% pool chlorinating liquid. It's 3.74 a gal and it's my go to product.
Wal-Mart also has Pool Essentials 2pk Pe Chlorinating Liquid(10%) at 6.44

Any unscented bleach (if it doesn't list % on container consider it 5% or less) concentrated will usually be ~ 8.25%

In all cases I order online and pick up in store because they may not have the quantities I want/need on the floor and I don't want to wait.
 

phappy

Well-known member
Aug 25, 2013
45
Battleofyakim, I'm in lower NY state. The pool gets plenty of sun during the day, but also times of shade as there are large trees around it (but they don't drop too much into the pool)

I was reading around the TFP site, and under the How to Chlorinate page it is suggested that typically you should "add about 2-3 ppm daily to keep the pool properly sanitized".

2-3 ppm. Seems a lot! Using the Pool Match calculator for my pool and CYA at 35, 3 ppm is 3 Quarts, 6 oz of 10% bleach. That is almost a full bottle every day? That is really costly at $3.50 or so a bottle.

Could this be correct?

What if you have a pretty well maintained FC level? Like for my pool 5 ppm FC is recommended. If it goes down only 1 ppm to 4 ppm, do you still put in the "typical" 2-3 ppm?