New pool owner -- need help understanding the SLAM process and CYA chart

[Soximus]

Hi,

I’ve run this test at least 15 times today, and have never gotten the same result twice! Occasionally there’ll be a few that are roughly the same, but the range of results is really incredible: all the way from 5.8ppm FC / 0ppm CC to 1.4ppm FC / 4.6ppm CC. I am very careful about sampling, and about filling the cylinder to exactly 25 mL before adding the R-0870 powder. I thoroughly mix the R-0870, and then I swirl the cylinder constantly as adding in drops of R-0871. I’ve learned that I need to do the R-0871 fairly quickly, as doing them too slow really inflates the drop count. After the water stays clear for 10 seconds, I add 5 drops of the R-003. Then I once again add drops of R-0871 while swirling constantly.

One thing that really baffles me is that the level of pink the water gets to after the addition of the R-0870 powder is wildly different from test to test. The instructions are pretty loose about the exact amount of R-0870 to use, which seems weird to me.

Any ideas about what’s going on here? The results are so different from test to test that I’m starting to wonder if one or more of the reagents is messed up…

 

[Texas Splash]

Let's use a standard ample size. The 25ML is extremely precise and not really needed. So do the following:

Get a 10ml water sample and add ONE generous scoop of powder. It should go Barbie pink. Then mix and add drops until clear. Once clear, divide # of drops in half. Example: 12 drops = an FC of 6. Be sure to get the water sample from the same spot in the pool. See if that helps.

 

[Soximus]

Hi all,

I am kicking myself for not coming to this site straight away! My pool chemistry is all over the place. CC is probably quite high (I'm trying to sort that out in a different thread), so I'm fairly certain a SLAM is in order. I'm sure the below questions are easily answered, but for whatever reason, I cannot get my head around a couple of basic TFPC techniques:

The Chlorine/CYA Chart: What is the "SLAM" tab actually telling me? I think I understand the "liquid chlorine" tab: At 40 CYA, I should aim for a minimum of 3ppm FC, with a target in the 5-7ppm FC range. But for "SLAM," is it saying that at 40 CYA, I want a FC level of 16ppm, I guess? Lastly, why does the "liquid chlorine" tab say that 30 CYA is not recommended, but then on the "SLAM" tab 30 CYA is OK? How does CC figure into this chart, if at all?

The SLAM guide: One minute into the how-to video, it says, "using pool math, figure out how much chlorine is needed to reach your shock level." I DL'd the pool math app , and If I enter an acceptable CYA level (30), and toggle "SLAM Target FC" on, the app does indeed suggest the same SLAM FC as is shown on the SLAM tab of the chlorine/CYA chart. However, the app then tells me that, to get from 3ppm FC (the current FC level) to my SLAM target of 12, I only need to add 33oz of 65% Cal-Hypo. That seems very low, to raise FC ppm by 9ppm...? I have a 17.7K gal pool. Am I just completely misunderstanding the directions of my 1lb Cal-Hypo 65% shock bags (a definite possibility)?

Another pool math app question: When I entered in a chlorine test result just now, I put in approximately where I think my CC is (3.0). I assumed the app would scream at me for that, but... nothing. Doesn't seem to show up anywhere in the overview. What gives? I definitely have "track combined chlorine" turned on in "pool settings," fwiw.

I have been careful about only adding chlorine at night (which, up until now, has been 65% Cal-Hypo granules). If my CYA is in range (30-50ppm), tho, would it be OK to add chlorine during daylight hours...?

Once I figure out the mechanics of starting the SLAM, how long do I keep FC at the SLAM level? Until the pool passes the OCLT? At that point, do I just let FC drift down naturally, or -- if I want to swim in the pool ASAP -- do I add something to bring the FC down faster, maybe? Related Q: I may have completely over-chlorinated my pool this evening. What's the best course of action, if I have?

The CC issue is particularly confusing to me; the other resources I've consulted talk about achieving "breakpoint chlorination" to deal with CC, which is (10 x CC) - current FC. So if I really do have 3.0 CC right now, I would calculate needing a FC of (30 - current FC), which just has to be higher than the SLAM FC of 12 the app is indicating. No? FWIW, the two resources I've looked at for how to deal with CC levels over 0.5 are the little booklet that comes with the Taylor K-2006 test kit and pages 3 & 4 of the Indiana State Department of Health "How to Shock the Pool (chlorinate to breakpoint)" documentation. Does the TFPC approach reject the whole "chlorinating to breakpoint" concept, maybe...?

THANK YOU, kind people, for any and all help. I have been tossing and turning for days on end, wondering if I'm ever going to actually get this job done... what an odyssey!

 

[Soximus]

Let's use a standard ample size. The 25ML is extremely precise and not really needed. So do the following:

Get a 10ml water sample and add ONE generous scoop of powder. It should go Barbie pink. Then mix and add drops until clear. Once clear, divide # of drops in half. Example: 12 drops = an FC of 6. Be sure to get the water sample from the same spot in the pool. See if that helps.

Thanks for the reply, Tex! I plan on doing this first thing in the morning... in the mean time, I think I have bigger fish to fry in terms of basic TFPC concepts (I started a new thread here; would love your input, if you have a minute). Regarding this thread: I found this TFP guide on how to conduct a FAS-DPD test, which is great, but nothing jumps out at me in terms of things I'm messing up about the testing procedure. Do people really get the same result twice if they run this test in quick succession?? It's wild to me how different the results have been! Any way, will report back when I run it again tomorrow AM...

 

[Flying Tivo]

You are mix and matching information. Its either pool store or TFP, no in-betweens. Re read ABCs of Pool Water Chemistry and follow videos on how to test. It can be confusing at first. CC are not that important, it just means your chlorine is working on organics. Do not use cal hypo, use liquid chlorine. My guess is that you are not doing the cc test imidiately after the FC test. If it turns pink again after you finish cc do not count that.

 

[Soximus]

You are mix and matching information. Its either pool store or TFP, no in-betweens. Re read ABCs of Pool Water Chemistry and follow videos on how to test. It can be confusing at first. CC are not that important, it just means your chlorine is working on organics. Do not use cal hypo, use liquid chlorine. My guess is that you are not doing the cc test imidiately after the FC test. If it turns pink again after you finish cc do not count that.

You're absolutely right-- I've just realized (over the course of the last 2.5 hours, as I've been obsessively reading posts here) that I'm definitely mixing and matching information. I had no idea there were so many different ideas about the "correct" way to treat a pool! One of the major problems I'm having is interpreting the baffling results from the many FAS-DPD chlorine tests I ran today. I started a thread on that issue here. I really feel as though I'm doing the test correctly (I've watched the Taylor instructional video and read this TFP page many times), and yet... my very inconsistent results would seem to indicate otherwise.

Any input on the importance of timing (night vs day) for adding chlorine, by the way? And if I find I've over chlorinated, should I just wait it out...?

 

[Krysib]

Any input on the importance of timing (night vs day) for adding chlorine, by the way? And if I find I've over chlorinated, should I just wait it out...?

You can add chlorine at any time of day-and during a SLAM should do so several times a day to ensure FC is never below the minimum level.
The advantage of nightly additions is there is no breakdown of chlorine from UV. But you need chlorine to stay high in a SLAM even during the day-so add away and assume quicker loss due to UV.

 

[Soximus]

You can add chlorine at any time of day-and during a SLAM should do so several times a day to ensure FC is never below the minimum level.
The advantage of nightly additions is there is no breakdown of chlorine from UV. But you need chlorine to stay high in a SLAM even during the day-so add away and assume quicker loss due to UV.

Fantastic-- thank you. Waiting around for night to fall was torture today! Glad I can be more assertive about it tomorrow, at least.

 

[pjt]

Use a SpeedStir or Smart Stir. It will greatly improve the speed, repeatability, and accuracy of your testing. Totally worth it.

Taylor Technologies 9265 SpeedStir Magnetic Stirrer Start-Up Pack with Stir Bar and Batteries: Swimming Pool Liquid Test Kits: Amazon.com: Industrial & Scientific

Taylor Technologies 9265 SpeedStir Magnetic Stirrer Start-Up Pack with Stir Bar and Batteries: Swimming Pool Liquid Test Kits: Amazon.com: Industrial & Scientific

www.amazon.com

Smart Stir Magnetic Stirring Device

tftestkits.net

 

[DeanP66]

I agree with pjt above. The speed (smart) stir works great and you can trust the fact that you'll get a consistent swirl every time. The water in the sample usually is a barbie pink, but if the FC is low, it may be a lighter shade. Definitely use the 10mL sample size. We aren't keeping our FC at 1 or 2 ppm here, so precision down to .5 per drop is more than good enough. Also, if you're not sure if you're done with the test, add one more drop and if that drop doesn't change the color any more deduct it from the total. Sometimes, you think you've cleared the sample with the R0871 drops, but there will be a faint little bit of pink. That's where adding the additional drop(s) can help you make sure you finish the test properly.

 

[Soximus]

I agree with pjt above. The speed (smart) stir works great and you can trust the fact that you'll get a consistent swirl every time. The water in the sample usually is a barbie pink, but if the FC is low, it may be a lighter shade. Definitely use the 10mL sample size. We aren't keeping our FC at 1 or 2 ppm here, so precision down to .5 per drop is more than good enough. Also, if you're not sure if you're done with the test, add one more drop and if that drop doesn't change the color any more deduct it from the total. Sometimes, you think you've cleared the sample with the R0871 drops, but there will be a faint little bit of pink. That's where adding the additional drop(s) can help you make sure you finish the test properly.

Thanks for this— A speedstir is on the way. That’ll definitely help; it does feel like the physical swirling is playing too idiosyncratic a role from test to test.

Regarding drops of R0871: on the first round of using it, for the FC test, it definitely seems like the solution goes back to pink if I just wait long enough. Is there a generally accepted amount of time it needs to stay clear before moving on to the CC portion of the test?

 

[Texas Splash]

it definitely seems like the solution goes back to pink if I just wait long enough

Don't let it just sit. Once it goes clear, record your FC and you're done. If you elect to run the CC test, go right into it after the FC test. Letting the sample sit will always result in the solution changing a bit.

 

[Texas Splash]

A few additional comments from your first post:
- Yes, add chlorine at ANY time you need to, especially during a SLAM. I would also rely primarily on liquid chlorine or regular bleach (same thing) and not use cal-hypo or any other bagged forms of chlorine on a regular basis. Those not only have side effects, but some of them can impact your CC level. That's why the liquid is so much better.
- The SLAM tab specifically addresses the elevated FC levels required to neutralize live algae. It's a scientifically proven ratio that works when maintained properly when balanced to the current CYA.
- We always maintain that FC SLAM level until all 3 SLAM criteria are complete.
- The Poolmath APP is a great tool. While it does provide some general highlights, warnings, etc, it cannot interpret all pool variables or scenarios. That's where we as TFP owners use our all of our experience to take appropriate action. For example, if you have a pool with a CH of 800, it might give a warning to exchange water. But if you live in AZ with exceptionally hard water, that may not make much of a difference. Instead we manipulate other chemical levels to compensate for that high CH and prevent scale. That's just one example, but there are others. So if you ever receive a Poolmath warning and aren't 100% sure if you should take action, just come back here and ask.
- I suspect some of your CC concerns might be related to using other forms of chlorine other than just liquid, so try to stick to just liquid chlorine/bleach for a few days and see if that helps resolve that issue.. That, coupled with a day or two of good sunlight should help to oxidize those CCs.

 

[Soximus]

Don't let it just sit. Once it goes clear, record your FC and you're done. If you elect to run the CC test, go right into it after the FC test. Letting the sample sit will always result in the solution changing a bit.

Got it. One of the major take-aways for me in all this is the the CC test is actually not necessary, if you’re following TFPC techniques and if you’ve got an outdoor pool where the sun will gradually reduce CC for you. Transitioning from the FC to CC test — with a certain amount of speed and swirling vigor — and trying to get both right is obviously more difficult than just doing FC and calling it a day… I wonder of this page could maybe mention that in the notes section?

I just did 3 tests, using the 10mL amount of water. All showed 5ppm FC (10 drops R0871). I did the CC on the third test, just for kicks: 1 drop/0.5ppm CC, and I *almost* didn’t add any R0871 at all since the sample was very nearly clear after adding the 5 drops of R003.

For the benefit of anyone who’s reading this and has experienced the same challenges with the FAS-DPD test: my best guess is that I wasn’t thoroughly cleaning the test vial between tests yesterday. I think there must have been residual reagent in the vial that was the main cause of the massively different results from test to test. Additionally, I most likely wasn’t swirling/dropping with the proper speed for the first few tests… so these things all added up to big errors. I’m still excited to have the SpeedStir on the way though… always nice to reduce the variables!

 

[Texas Splash]

I just did 3 tests, using the 10mL amount of water. All showed 5ppm FC (10 drops R0871). I did the CC on the third test, just for kicks: 1 drop/0.5ppm CC, and I *almost* didn’t add any R0871 at all since the sample was very nearly clear after adding the 5 drops of R003.

Great!

 

[Soximus]

A few additional comments from your first post:
- Yes, add chlorine at ANY time you need to, especially during a SLAM. I would also rely primarily on liquid chlorine or regular bleach (same thing) and not use cal-hypo or any other bagged forms of chlorine on a regular basis. Those not only have side effects, but some of them can impact your CC level. That's why the liquid is so much better.

You’re referring to stabilized forms of granular chlorine, right? Or… are there side effects from using non-stabilized bagged chlorine, too?

…That's just one example, but there are others. So if you ever receive a Poolmath warning and aren't 100% sure if you should take action, just come back here and ask.

I have to say, this is such a fantastic thing to hear, as someone starting out as pool owner/maintainer. Thank you very much. I will try my best to use the search bar, but it’s totally reassuring to know that newbie questions are ok!

- I suspect some of your CC concerns might be related to using other forms of chlorine other than just liquid, so try to stick to just liquid chlorine/bleach for a few days and see if that helps resolve that issue.. That, coupled with a day or two of good sunlight should help to oxidize those CCs.

Got it— will do. My understanding is that “liquid chlorine” and “liquid bleach” are chemically identical, but that LC is a much higher %, whereas LB is in the 5-6% range. Is that right? My wife is going to flip out if I start dumping bleach in the pool, so I figured I’d better double check! Along these lines: if I monkey with the test results a bit, I can get the pool math app to recommend an addition of bleach. The app also allows me to specify what % bleach chlorine I’ll be using. Do I have it right that whether I’m using “liquid chlorine” or “bleach,” it’ll always be called “bleach” in the app… and I’ll just manually change the “bleach chlorine” % to match whatever the packaging is telling me? Lastly, I gather that the majority of TFP users favor regular 5-6% liquid bleach over liquid chlorine, on account of the lower price for bleach (even after accounting for how much more you need of it, in terms of raw volume)…?

 

[Texas Splash]

You’re referring to stabilized forms of granular chlorine, right? Or… are there side effects from using non-stabilized bagged chlorine, too?

I am referring to stabilized chlorine like those bags of shock at the pool store that either have CYA or calcium by-products in them.

My understanding is that “liquid chlorine” and “liquid bleach” are chemically identical, but that LC is a much higher %, whereas LB is in the 5-6% range. Is that right?

Correct!

I don't recall what the APP lists as a choice (chlorine/bleach) but they are the same thing with the exception of %. If you use laundry bleach, be sure to NOT grab Clorox and do NOT use any bleach that has splashless, scented, or fabric enhancements on the label. You want regular/plain.

 

[Soximus]

… If you use laundry bleach, be sure to NOT grab Clorox and do NOT use any bleach that has splashless, scented, or fabric enhancements on the label. You want regular/plain.

You’ve guessed exactly what I was wondering… have you been helping folks like me for a while, maybe?

Thanks again for all the help. I was feeling pretty low about all this yesterday, what with the crazy test results and the pleading eyes of my children looking at me in silence while I swirled vial after vial of FAS-DPD test, like some kind of incompetent mad scientist… can’t tell you what a relief it is to be back on track!

 

[BassPlayingDude]

In my area, the 6% bleach is not always cheaper than buying the 12.5% shock. I also prefer the 10% or 12.5% concentration because it means fewer jugs to lug. YMMV.

 

[Soximus]

In my area, the 6% bleach is not always cheaper than buying the 12.5% shock. I also prefer the 10% or 12.5% concentration because it means fewer jugs to lug. YMMV.

That makes sense. I would think concentrations above 6% are only found in pool stores... right?