Help with chlorine demand - ammonia?

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insomnia

Member
Jul 12, 2020
9
Massachusetts
Hello,
I am experiencing some low FC high CC problem, and pool store's suggestions didn't seem to help, so on my journey of reading everything on the internet. At last decided to get a TF100 test kit, and an API ammonia test kit, and hopefully TFP can help!
Got a 26,000 gallon pool, opened it on 7/4, not green at all and usual cloudiness, added 4 gallons of 12.5% liquid shock running filter 24/7.
Tested water at pool store on 7/6, test result:
FC 0.69, TC 7.58, PH 7.4, TA 63, CYA 7
Pool store said that's a chlorine lock so I did 5lbs of none chlorine shock... for the next few days, added alkanility, added cyanuric acid, 2 more session of 6lbs of none chlorine shock....
Did a couple more water tests at pool store in that time period, TA raised to 83 then dropped to 75, saw CYA level raised to 42 then dropped to 17. The whole time big differences between FC < 1and TC > 8. Ph fairly stable around 7.5.
Nothing makes sense to me!
The water is now very clear, although the wall feels a little slimy. No algae, although some part of the pool liner looks yellowish, but that appeared last year, which also had a bout of FC/TT chlorine differences, but got stable after using the none chlorine shock, I think that was the reason.
Now I read about ammonia, and how bacteria might convert CYA to ammonia, and it could also consume chlorine, so I want to follow the SLAM process and see if I can get the chlorine right again.
Here are the results from the TF100 and API tests:
FC 4.5, (CC 1) TC 5.5, PH 7.6, TA 120, CYA < 20, AMMONIA > 8.
Is any of these making any sense to anyone? :)
Would the SLAM process be able to fix the chlorine?

Thank you,

Pak
 
Welcome to TFP.

If your water holds chlorine, which yours does, then you don’t have an ammonia problem.

Now that you have your TF-100 follow the SLAM Process exactly step by step with no shortcuts.
 
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Thank you for the info!

Is it safe to swim in the water has these numbers? FC 4.5, (CC 1) TC 5.5, PH 7.6, TA 120, CYA < 20, AMMONIA > 8.

Should I only SLAM during the evening since my CYA is not between 30 to 40 according to the process? Also, I last week I added 4lbs of cyanuric acid, it went from 42 but dropped to < 20, shouldn't CYA only increase until draining the water? Or is bacteria really do convert CYA to ammonia?
 
If you have ammonia you would have 0 FC, 0 CYA, and low pH, and you don’t.

The SLAM Process takes multiple days. Once you begin you MAINTAIN the SLAM FC level until you satisfy the three exit criteria.

Your pool is safe to swim in if you can see the bottom of the deep end.
 
I had begin the SLAM process. Last evening before starting, retested water with TF100, resulting in
FC: 1.5
CC: 2.5 (TC 4)
PH: >= 7.8
TA: ~95
CYA: ~15
I had added about 3lbs of sodium bisulfate hope to reduce PH to the recommended 7.2 ~ 7.5 range.
After an hour or so, added slowly at returns total of 2 gallons of 12.5% liquid shock, calculator say 1.8 gallons, I think it's close enough, hope that won't make much difference.

This morning I did another test, here are the results:
FC: 4
CC: 5 (TC 9)
Looks like I still need to do another round of shock today with about 1.3 gallon of liquid shock.
Does that sound right?
With those chlorine level, is it ok to swim in the afternoon before I shock again?

A newbie question regarding testing, when testing FC, after the water turns pink after adding R-0870 Powder, then I proceed to add and count R-0871 drops, the confusion I have is sometimes it looks clear but then I still see a hint of pink, and if I keep trying to determine if it's clear or not, it then turns more pink, possibly from some undissolved powder, then I would add more drops, but then the solution seemed cloudy. My quesiton is at which point is clear and count the drops? As per the instruction pointed out, not all the DPD will dissolve at first, this could be the cause of pink returning?

It's good to have a place to ask for directions and get trust worthy answers! Thanks you.
 
insomnia said:
With those chlorine level, is it ok to swim in the afternoon before I shock again?
Click to expand...

Any FC level up to SLAM FC level is safe to swim in. And with any CC. As longa s youc an see the bottom of the deep end of the pool.

The more often you check the Fc level and raise it back up to SLAM FC the faster the SLAM Process will go.

insomnia said:
A newbie question regarding testing, when testing FC, after the water turns pink after adding R-0870 Powder, then I proceed to add and count R-0871 drops, the confusion I have is sometimes it looks clear but then I still see a hint of pink, and if I keep trying to determine if it's clear or not, it then turns more pink, possibly from some undissolved powder, then I would add more drops, but then the solution seemed cloudy. My quesiton is at which point is clear and count the drops? As per the instruction pointed out, not all the DPD will dissolve at first, this could be the cause of pink returning?
Click to expand...

Add R-0871 until a drop does not change its color then subtract that drop. If you let the clear solution sit around it will turn pink again. Ignore that. Do the drops, see the change, stop and record the amount. Using the Speedstir Magnetic Stirrer-IN STOCK helps with the repeatability of the testing versus swirling.

 
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insomnia said:
Got a 26,000 gallon pool, opened it on 7/4, not green at all and usual cloudiness,
Click to expand...
Welcome to TFP! Follow the advice given here, and you'll quickly learn that cloudiness is not at all usual for a TFP pool! We have a thread about that. Here's my pool, picture taken two days ago, pool up for one month.
full


ajw22 said:
Add R-0871 until a drop does not change its color then subtract that drop.
Click to expand...
If you do that on the FC test, isn't that like adding an extra drop on the CC side of things? I.e. if it goes clear on the FC and you add one extra drop, then follow with the CC test you'd have to take 0.5 ppm off the CC test results, right? Plus if you had 0.5 ppm CC or less you couldn't tell if you had no CC or just 0.5 or less.

I did watch the video and I note they say to add an extra drop on the CC test to be sure it's clear, but they don't say the same on the FC test.
 
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jseyfert3 said:
If you do that on the FC test, isn't that like adding an extra drop on the CC side of things? I.e. if it goes clear on the FC and you add one extra drop, then follow with the CC test you'd have to take 0.5 ppm off the CC test results, right? Plus if you had 0.5 ppm CC or less you couldn't tell if you had no CC or just 0.5 or less.
Click to expand...

No, I think the CC test only counts the T-0871 drops needed to neutralize the R-0003 reagent you add.

jseyfert3 said:
I did watch the video and I note they say to add an extra drop on the CC test to be sure it's clear, but they don't say the same on the FC test.
Click to expand...

Add the extra drop if you are in doubt. +/- 1 drop really does not make a difference in the testing. If 1 drop does make a difference you are running your FC too close to the limits.
 
ajw22 said:
No, I think the CC test only counts the T-0871 drops needed to neutralize the R-0003 reagent you add.
Click to expand...
ajw22 said:
Add the extra drop if you are in doubt. +/- 1 drop really does not make a difference in the testing. If 1 drop does make a difference you are running your FC too close to the limits.
Click to expand...
Hmm. I'm pretty certain I've added extra drops on accident to the FC test (after it went clear) and gotten 0 for CC's I know I had. That's why I'm bringing this up. It's not that you're running too close to the FC limit but that you could incorrectly not show CC's that you might have.

I guess I have an experiment to run the next time I'm testing and CC's are present. Unless @JoyfulNoise knows off the top of his head.
 
@jseyfert3

Adding the extra drop on the FC side of the test does not effect the results on the CC side of the test. I'd rather not side-track this thread with a discussion of the details of DPD Chemistry for Chlorine analysis. If you're interested, post a question in the Deep End and I'll answer it there.
 
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On 7/21 I added cyanuric (dry) acid to bring up CYA from 15 to 30, so I can SLAM during the day time as well.

Finally on 7/22 8:30PM I had clear the SLAM's criteria of CC < 0.5.
So on that same night, I started OCLT, with these test results:
FC: 4.5
CC: ~0.5
AMMONIA: < 0.25

Waking up early on 7/23 5:30AM having great hope that it's going to be a good test, but...
FC: ~0.5
CC: ~0.5

I guess there are still things in the pool that are reducing the FC? but how come CC stays good though?

So I continue SLAM, at 9AM, I added 2.5 Gallon of 12.5% liquid shock according to pool math to get FC to 12.

Tested again at 11:30AM, resulting in
FC: 7
CC: ~ 0.5
AMMONIA: < 0.25

Is the drop from 12 (@9AM) to 7 (@11:30AM) expected or abnormal in anyway? We do have good sun past couple of weeks.

At 12PM I shock again with 1 Gallon of 12.5% liquid shock to keep FC at 12. Will test again later.

Tested again at 5:00PM, results:
FC: 6
CC: 0.5

Let me know if I am doing something wrong! Thanks.
 
Last edited:
Ok, maybe it's a turning point.

On 7/23 tested again at 5:00PM, results:
FC: 6
CC: 0.5

and the next morning at 8:00AM, results:
FC: 4
CC: 0

Losing 2 FC over 15 hours, looks like end is in sight, will keep up at SLAM today, and do OCLT one more time.
 
The key to the SLAM is the maintain part (one of the keys at least). Get your FC to 12 and keep it there. BTW keeping there for a couple of days or so after you pass an OCLT is not a bad idea either.
 
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Another way to look at it is that you lost 1/3 of your chlorine over that time. You really need to keep it at 12, testing 4 or more times a day, and adding every time to get back to 12. The less vigilant you are, the longer the process takes.

How is your water looking?
 
The good news, this morning it passed the OCLT. :) , water is clear and no more CC. I can't tell you how happy I am right now. Thanks all for sharing your experience and knowledge, that really helped me. And yes, just keeping the shock level more frequently was the key.
 
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