Next steps? Algae seems gone after 12 day SLAM

jrmacleod

Member
Sep 10, 2018
12
Charlottetown
Hi, my SLAM may be coming to a close after about 12 days. Pool water is crystal clear blue, and I have a solid test kit in place now so here is what I'm looking at and would appreciate guidance on next steps:

Yesterday at 330pm test results (after 2 days of adding no more Chlorine which was previously at SLAM level):
FC 4.3
CC 0.2
pH 7.9
TA 161
CH 266
CYA 20

I put in recommended liquid bleach to bring FC up to SLAM 10 level one more time. Maybe bleach amount added was a bit lower, but here is the test result I got at 509pm:
FC 8.2

Just went out and tested this morning 12 hours later at 549am and here are my latest results:
FC 7.3
CC 0.3
pH 8.3
TA 164
CH 324 (surprised at jump maybe I did wrong)
CYA 22

My CC is well below 0.5, my FC dropped 0.9 overnight 12 hrs, and pool is clear. My CY is low so that would likely cause FC to drop a little faster also?

Question: can SLAM end and now I work on getting better balance? And what should I start with?

Thanks!
Justin
 

jrmacleod

Member
Sep 10, 2018
12
Charlottetown
Besides Calcium which I think I did wrong, what test results are all over the place?

FC obviously will fluctuate as I added bleach for SLAM.
CC 0.2 and 0.3 not a big difference.
pH 7.9 and 8.3 likely due to adding SLAM level of chlorine
TA 161 and 164 within 2% difference
CY 20 and 22 again fairly close

Are those differences very major and out of line with normal testing margins of difference?
 

aeh0603

Well-known member
Apr 6, 2016
351
San Diego, CA
The test kits we recommend cannot produce test result numbers that look like that.

I see in your signature that you have an iDip digital test kit. I'm not entirely sure how that one works. It is a digital test strip reader?
 

jrmacleod

Member
Sep 10, 2018
12
Charlottetown
With the very most of respect to the knowledgeable folks here, I'm actually just looking for help with next steps and not start a discussion/debate about the accuracy of different types of test kits.

To work towards that end though and to (hopefully) satisfy that my test kit is producing accurate results, let me clarify what I'm using and a few things about it.

I am using an eXact iDip® Smart Photometer. The method it uses is you take pool water samples, and rather than putting liquid reagent into the samples like the Taylor kits, the reagent is taken off a factory manufactured test strip with an exact amount of reagent on the strip. The reagent mixes with the pool water sample (of a very specific and measured size), and then the photometer digitally reads the colour of the resulting water, and produces a reading. The device is capable of measuring all the required pool water measurements and also can be used for other measurements for Spas, well-water testing, aquarium water testing and even beer production. You simply buy the additional required tests and reagent strips.

In terms of accuracy... don't take my word for it... the NSF which is an independent testing body since 1944, has specific levels of certification in place for this type of test called NSF-50 (for example free chlorine and pH in Pool water, a separate standard for Spa water, etc. These certifications for helping ensure public safety in swimming pools, spas etc.)

Based on these certification levels, testing kits can score Levels 1,2,3 (L1,L2,L3) with L1 being the most accurate, L2 the next best, then L3 certification.

The full list of products currently certified by NSF for Pool and Spa water testing are listed here:

As you can see on that list, the Taylor Technologies kit that is promoted here (and I don't doubt it is excellent), the K-2006 and K-2006C, are certified by NSF at L2 or Level 2 for total chlorine and also for free chlorine in pools. It is certified at L3 for CYA and pH. What this means specifically for FC and CC is that L2 accuracy is within +/- 1.0 ppm for readings between 3 and 5, and it is accurate within +/- 2.5 ppm for readings between 5 and 10.

The iDip kit which I am using, which I have seen being dismissed on these forums as "not good enough" as all digital kits seem to be "lumped in together" as inaccurate, is actually certified by NSF as Level 1 (L1) for Free Chlorine and pH, and L2 for combined chlorine and CYA. Both more accurate than the Taylor kit. This L1 certification means for accuracy for FC, it is accurate within +/- 0.2 ppp for readings form 0-3, within +/- 0.7 ppm for readings from 3-7, and within +/- 1.5 for readings from 7-10.

In summary: the same NSF independent testing body, established since 1944 and responsible for independently certifying products for health and safety around the world, has published that the iDip kit I'm using, is CERTIFIED as more accurate than the Taylor K-2006 and K-2006C kits.

Now one question that comes up is "what about calibration?"... don't those meters need to be calibrated? Yes, they need to be calibrated, but the product includes a standard colour test kit in the package that enables one to run a calibration test at any time to ensure the device is properly calibrated. I have run that test several times and it has given the exact same and correct calibration reading, exact to the 0.01 ppm on the test every time I have run it.

With all that said, I submit that I'm personally confident in the accuracy of the device. Perhaps I am wrong and I will admit I am not an expert, and do defer to the experience in these forms, but to me the science and process used by NSF has to mean something and they certainly are also experts in the field I'm relying on.

The exact iDip product I'm using is designed and manufactured right in Rock Hill, SC in the USA and the company has won numerous awards and has been established since 1989 and has industry leading water testing products.

Sorry for the long explanation and honestly I hoped to avoid a discussion about whether my test kit is accurate or not, but for the sake of next steps would it be possible to just take a leap of faith and assume the results are accurate? If they are, then based on my initial questions I'd really like to get some help with next steps.

You did mention that with the test kits that are promoted here, one would never get results like I got. I'd be interested for some clarification on that, and also with guidance on next steps if possible.

Thanks!
 

duraleigh

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Apr 1, 2007
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No discussion on accuracy from this forum on the IDip. The vast majority of us have never heard of it so can't pass on any valid opinion.

We can give you a thousand opinions on kits we are familiar with but it sounds like you are asking us to opine on something we know nothing about.

I would also ask you to read rule #6 of our forum rules. The sole purpose of your post seems to promote a product which is simply against the rules.
 
Last edited:

duraleigh

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Are those differences very major and out of line with normal testing margins of difference?
Yes. pH testing of 8.3 and then 7.9 the next day is wa-a-ay out of normal and it is not related to the addition of FC which is essentially pH neutral.
 

aeh0603

Well-known member
Apr 6, 2016
351
San Diego, CA
Ok, thank you for the explanation. Idip not a tester I have heard of before or seen discussed on this site so I was curious.

As for your SLAM, there are 3 criteria you must meet to end a SLAM
1) clear water - this refers to both clarity (should be able to read heads or tails of a coin in the deep end) as well as visible algae (if you see algae you fail the clear water test)
2) CC at or below 0.5
3) pass OCLT (FC loss of 1 or less overnight)

Per your description it sounds like you pass all 3 and can end your SLAM.

Yes. pH testing of 8.3 and then 7.9 the next day is wa-a-ay out of normal and it is not related to the addition of FC which is essentially pH neutral.
I read this as the other way around. pH was 7.9 yesterday and 8.3 today. With a high TA this seems reasonable.

I don't know enough to comment on the validity of the iDip, but assuming it's accurate...
As for next steps, pH should be lowered to the 7s and CYA should be raised to at least 30 to protect your FC from the sun. If you are losing more than 4 FC in 24 hours, but pass the OCLT, then raise CYA by an increment of 10 and re-evaluate. Maintain your FC daily per the FC/CYA chart.
 

aeh0603

Well-known member
Apr 6, 2016
351
San Diego, CA
You did mention that with the test kits that are promoted here, one would never get results like I got. I'd be interested for some clarification on that
The Taylor k2006 / k2006C, and TF100 test kits are primarily drop based titration tests. For FC/CC, depending on which water sample size you use results are either in increments of 0.2 or 0.5. having a result end in 0.3 is not possible. Similarly, the CH and TA tests are in increments of 10 or 25. The CYA test is a turbidity test with results in increments of 10. Any result between two lines on the tube is rounded up to the nearest 10.

These results have more than enough accuracy and precision for home pool maintenance.

I'm trying my best to help you out and give you the benefit of the doubt, but if you have read other posts on this forum it shouldn't surprise you that your test kit is being questioned. We question everyone ?. We also don't generally offer advice based on test results we don't trust and without knowing much about the tester you have, the folks on this forum are not likely to blindly trust it. Even if it's as accurate as you say, we simply don't know the limitations associated with it. For example we don't know the upper limit of accuracy for the FC test, many are not accurate over 10. We also don't know if high levels of FC cause interactions with the other tests.
 

jrmacleod

Member
Sep 10, 2018
12
Charlottetown
No discussion on accuracy from this forum on the IDip. The vast majority of us have never heard of it so can't pass on any valid opinion.

We can give you a thousand opinions on kits we are familiar with but it sounds like you are asking us to opine on something we know nothing about.

I would also ask you to read rule #6 of our forum rules. The sole purpose of your post seems to promote a product which is simply against the rules.
Duraleigh, with all due respect... I have no affiliation with the iDip company, and I specifically made my post not mentioning it. I hoped to not have to get into that discussion. Wasn't until I was asked about my test kit that I felt the need to provide the info I did. If that breaks the rules, I'm sorry. There certainly are plenty of posts "promoting" the TF-100 and Taylor kits, but like my post I don't take them as promotional, just trying to provide information to help.

And yes, there has been discussion on the forums about the exact photometer products... I read those posts here before deciding to buy it! One in particular from a trained chemist who had also purchased it for his pool. However there were negative comments about it being a "digital tester, not accurate, etc." which he also had to defend the technology similar to what I did.

Sorry if you're not willing to "opine" because I'm using a different testing technology. My questions are more about here are my testing results, what do you suggest.... not a discussion about whether my results are accurate.

Regarding your comment that chlorine would not affect pH values... that isn't what I read in the ABC's of chemistry on this site or the SLAM how-to articles... they specifically say that pH testing can be way thrown off and unpredictable during the SLAM process. Go ahead and check the articles.

This is why I hesitated posting here in the first place. I thought I would probably get heckled because of my test kit. While I know you are familiar with what you use, I'm just trying to get some help and have gone a different way with the testing technology. I would respectfully submit (even though I'm a newbie here) that there should be room enough for more than one testing approach on this site. Especially one that's been independently scientifically verified as equally or more accurate.

Ok that's off my chest. I really need to stay off forums as the flame wars just bug me, especially when I become part of one.
 

jrmacleod

Member
Sep 10, 2018
12
Charlottetown
The Taylor k2006 / k2006C, and TF100 test kits are primarily drop based titration tests. For FC/CC, depending on which water sample size you use results are either in increments of 0.2 or 0.5. having a result end in 0.3 is not possible. Similarly, the CH and TA tests are in increments of 10 or 25. The CYA test is a turbidity test with results in increments of 10. Any result between two lines on the tube is rounded up to the nearest 10.

These results have more than enough accuracy and precision for home pool maintenance.

I'm trying my best to help you out and give you the benefit of the doubt, but if you have read other posts on this forum it shouldn't surprise you that your test kit is being questioned. We question everyone ?. We also don't generally offer advice based on test results we don't trust and without knowing much about the tester you have, the folks on this forum are not likely to blindly trust it. Even if it's as accurate as you say, we simply don't know the limitations associated with it. For example we don't know the upper limit of accuracy for the FC test, many are not accurate over 10. We also don't know if high levels of FC cause interactions with the other tests.
Thanks so much aeh0603, that is extemely helpful! I completely understand where you're coming from. I guess I've felt a bit defensive as I spent a lot of time researching the iDip test kit, forked over good cash for it, and then was expecting to get negative comments about it... I can see why people would have trouble instantly accepting it, and maybe in the end they are right! :) But I hope it proves to be accurate. I will take the next steps you suggest and hope to be enjoying a nice swimming experience soon!

J
 

aeh0603

Well-known member
Apr 6, 2016
351
San Diego, CA
Regarding your comment that chlorine would not affect pH values... that isn't what I read in the ABC's of chemistry on this site or the SLAM how-to articles... they specifically say that pH testing can be way thrown off and unpredictable during the SLAM process.
Chlorine does not affect actual pH values. It does affect the accuracy of the pH test when FC is over 10... At least for the recommended test kits... I don't know how it would impact the iDip.
 

Casey

TFP Expert
LifeTime Supporter
Apr 16, 2007
11,497
SW PA
You mentioned you added your FC for the night at around 8pm. I'm in Pennsylvania and it's still daylight at that time so I think you would be better served to add your FC in the dark to completely eliminate any uv degrading. This is what I do. So it wouldn't hurt to do it again. I can not answer on your test kit as I am an avid user of the TF100 for the last 15 years or so. I just saw that you added at 8pm and it's still light out.
 

jrmacleod

Member
Sep 10, 2018
12
Charlottetown
Chlorine does not affect actual pH values. It does affect the accuracy of the pH test when FC is over 10... At least for the recommended test kits... I don't know how it would impact the iDip.
Ahhh thanks for the clarification. I'm not sure how it would affect the iDip pH test. One disadvantage of the iDip vs. the TF100 or Taylor kits is that it only measures FC up to 12 (rather than 25). For my purposes I accepted that limitation though as my SLAM level is normally going to be only 10 or 12 FC.
 

jrmacleod

Member
Sep 10, 2018
12
Charlottetown
You mentioned you added your FC for the night at around 8pm. I'm in Pennsylvania and it's still daylight at that time so I think you would be better served to add your FC in the dark to completely eliminate any uv degrading. This is what I do. So it wouldn't hurt to do it again. I can not answer on your test kit as I am an avid user of the TF100 for the last 15 years or so. I just saw that you added at 8pm and it's still light out.
Got it, thanks for the tip to wait until after dark. Yes it is light here well beyond 8pm now. I'll keep that in mind!