Ta - should I bother reducing?

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novice123

Well-known member
May 11, 2023
54
UK
Pool Size
15200
Chlorine
Liquid Chlorine
Long story short about a year and a half ago approx found this forum and learnt a great deal and carried out the slam process. Everything was perfect then after a month or so pool had a leak! After getting so many people to come and have a look it is now finally repaired (for good I hope).

the pool was emptied and cleaned thoroughly and then refilled. I added stabilised chlorine granules 5ppm three times. And then I just left everything for a few days (went away due to work). Came back today and here are the results:


Ta 167
Cc 0.11
Fc 0.02
Cya 9
Ph 7.9

I don’t bother checking for water hardness as it’s very hard water and here and I can’t find a solution that is within something I can afford.

Question is Ta is quite highly but ph is only slightly high. I remember lowering the Ta last time and then aerating to increase ph but aeration seems to be more an art than science. Is it ok if I just bring ph down slightly and leave the Ta as it is? Poolmath is saying to add 201g of dry acid to reduce the Ta.

Please advise!
 
You need a proper test kit. Might take some effort given your location, but it's worth it.

You need chlorine ASAP as well as CYA (enough to achieve ~40).

Use muriatic acid instead of dry acid.
 
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Rancho Cost-a-Lotta said:
I would not worry about TA. Just keep pH in range and monitor TA. If you have high TA fill water and it continues to rise, take more aggressive measures in the future.
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So based on your advice I checked 9 hours after adding 10ppm stabilised chlorine granules and tested for fc cc and cya again and here are the results

Fc: 3.74
Cya 23
Cc 3.82

I should add the kids went in for a swim too so that probably ate up some of the fc.

Cya:
So in total now I have added since the pool was completely refilled 25ppm stabilised granules (150g to raise 5ppm so 750g) . This has raised the cya from zero to 23. That would mean 750g / 23 = 32.6g. So 32.5g of the stabilised chlorine granules raises cya by 1? Is that right or have I completely lost it? If that is the case and I need a target of 30 cya I need to raise cya by 7 therefore 32.6 x 7 = 228.27g of granules.

Of course this will raise the fc too by 7.6. If then I needed to raise th fc further that would mean it needs to be liquid chlorine or non stabilised granules? Is that correct?

Fc
Should I raise the fc back to 10ppm? How long should I do this for? As in what is the threshold after which I can let Fc come down to 3 and maintain it at that?

Mind you the water is crystal clear atm.

Many thanks in advance!

I’ll slightly adjust the ph to bring it back down within acceptable parameters.
 
How are you testing your water. Are you using a FAS/DPD free chlorine test kit?

How do you plan to chlorinate the pool in the future? We recommend liquid chlorine or a SWG system.

novice123 said:
stabilised chlorine granules
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Is this dichlor?
novice123 said:
Fc: 3.74
Cya 23
Cc 3.82
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Your FC is 3.74?
CC is combined chloramines. Is that number really 3.82 or did you mean TC or total chlorine?

Raise your CYA to 30 ppm. If it's available, use 100% cyanuric acid (chlorine stabiliser). Maintain FC according to the FC/CYA Levels. Don't tread around minimum level. Stay well within target level. Use liquid chlorine or invest in a SWG.

Since your FC levels dropped so low, it was be a good idea to rule out algae by completing an Overnight Chlorine Loss Test.
 
Rancho Cost-a-Lotta said:
How are you testing your water. Are you using a FAS/DPD free chlorine test kit?
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I’m using the pool lab 2.0. I know this isn’t the proper tfp method but I tried getting my hands on that test kit last time and wasn’t able to source it so I just went with this after seeing reviews and tests where it showed that though the pool lab yields different results the margin of error is minimal e.g 3.2 vs 3.3.

Rancho Cost-a-Lotta said:
How do you plan to chlorinate the pool in the future?
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In the beginning I used liquid chlorine 16% as it’s sold here but when Covid hit it wasn’t available for a while so I switched to calcium hypochlorite granules and bought tubs of it as I feared even this would go out of stock 😬.

So after cya reaches the desired level I will switch to Cal Hypo. Problem is I already have very hard water here and this would just make things worse. The only issue I fear with liquid chlorine is the shelf life. My son accidentally left a whole drum in full view of the sun and then I had to add the whole contents about 15 litres to see any noticeable difference. And the price of it has doubled!

Rancho Cost-a-Lotta said:
Is this dichlor?
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Yes. Only using this to raise the cya.
Rancho Cost-a-Lotta said:
CC is combined chloramines. Is that number really 3.82 or did you mean TC or total chlorine?
Click to expand...
Good catch! I meant TC not CC. 🤦🏽
Rancho Cost-a-Lotta said:
Raise your CYA to 30 ppm
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since I added dichlor today and it raised it to 23 should I wait a few days since apparently cya doesn’t show up altogether and can take a few days?

Also my pool is inside an acrylic enclosure (looks like glass but it’s acrylic). Does that mean I can get away with 23 since I’ve read for indoor pools 20 is sufficient (but my pool is neither completely an “indoor” pool nor an “outdoor” pool. If so i can switch to cal hypo or liquid chlorine from here on.

Rancho Cost-a-Lotta said:
Since your FC levels dropped so low, it was be a good idea to rule out algae by completing an Overnight Chlorine Loss Test.
Click to expand...
Apologies if this is an obvious question, but since the overnight chlorine loss test is often mentioned in conjunction with the slam method: for this test, i simply take a reading at sunset, and take another reading at sunrise, and note the difference? In other words, I don’t have to raise the chlorine level to a specific level for this test?

I have a uv sanitiser too to help with the algae and cc. Just mentioning if that makes any difference.
 
novice123 said:
Apologies if this is an obvious question, but since the overnight chlorine loss test is often mentioned in conjunction with the slam method: for this test, i simply take a reading at sunset, and take another reading at sunrise, and note the difference? In other words, I don’t have to raise the chlorine level to a specific level for this test?
Click to expand...
Correct. No need to raise fc.

Your acrylic enclosure is a new one for me. I'm not sure if it blocks UV. If so, then you can handle it as an indoor pool and your UV sanitizer would actually do some good. Either way, maintaining CYA at 30 ppm removes any guessing from the equation.

Calcium hypochlorite would be my third choice for chlorination behind liquid chlorine and SWG. With a polymer pool, high CYA is more of a menace than high calcium.
 
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Rancho Cost-a-Lotta said:
Your acrylic enclosure is a new one for me. I'm not sure if it blocks UV.
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From my reading I understood that even though my pool is enclosed in transparent acrylic, UV rays can still penetrate to some extent depending on the quality and thickness of the acrylic and its UV filtering capabilities. Acrylic, similar to glass, filters out a portion of UV rays but not entirely. In enclosed pools, especially those with transparent enclosures, some UV protection is provided, though it is not as effective as in fully shaded or indoor pools with solid roofs. Therefore, while UV exposure is reduced compared to outdoor pools, there can still be some degradation of chlorine over time due to UV exposure through the acrylic enclosure. In other words as you said keep cya at 30 lol

Also I’ve read on here that cya can take time to increase so should I wait a day 2 days before I try to raise it again?
 
I have high TA from my water source. This slowly causes PH to rise, especially if air is bubbling through the water or the pool is getting used. This slowly reduces the TA. I then periodically add muriatic acid to get the PH to balance. Eventually, the TA gets somewhere below 100 and the PH rise stops occurring. If refilling my hottub, this whole process can be done in one day but for my pool it goes on for weeks (or more if adding water due to evaporation). Just mentioning this in case you notice PH rise and are investigating why.
 
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Rancho Cost-a-Lotta said:
I would not worry about TA. Just keep pH in range and monitor TA. If you have high TA fill water and it continues to rise, take more aggressive measures in the future.
Click to expand...
The tap water here has high Ta. I noticed ph is slightly on the rise. Is it worth me bringing this down from 183 to 120 then aerate to raise ph? Then I will ensure cya is 30 and then start the slam?
 
The water is very clear but yday I raised chlorine to 10ppm then today roughly 24 hours or so later it came down to 2.33 = need to slam.

But since no visible algae should I reduce the ta? Just worried about the rising ph and possible scaling

I should add cya was 23 (went down since I last tested)
 
Scaling? What scaling? What scaling are you worried about.

Are you using pool math? If not get it. Link-->PoolMath

Login with same login as TFP.

Configure your pool and enter your most recent results.
Go to gear in upper right, scroll to Track, enable temperature and enable CSI.
Scroll further down and enable sharing with TFP. Then we can see your chemistry to see if scaling is even an issue. Usually scaling takes longer to form than the duration of the SLAM. We can deal with that after SLAM.

For the slam, TA is not an issue. When you do SLAM turn off the UV.
 
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PoolStored said:
Scaling? What scaling? What scaling are you worried about.

Are you using pool math? If not get it. Link-->PoolMath

Login with same login as TFP.

Configure your pool and enter your most recent results.
Go to gear in upper right, scroll to Track, enable temperature and enable CSI.
Scroll further down and enable sharing with TFP. Then we can see your chemistry to see if scaling is even an issue. Usually scaling takes longer to form than the duration of the SLAM. We can deal with that after SLAM.

For the slam, TA is not an issue. When you do SLAM turn off the UV.
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Sorry I should clarify, not scaling as in the next few days but long term. I realised I merged two questions into one, sorry!

So for the slam adjusting ta isn’t required but in general aside from the slam is it worth taking it down to 120 that was my initial question. Then I realised the ph is slowly creeping up and hence I wanted to know should I adjust it? The only pain in the behind with this is it lowers ph which I have to raise through aeration which can take hours….

Curious to know though why should the uv be turned off?
 
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novice123 said:
Where does this leave me with my uv system? I’ll turn it off during the slam but afterwards should I only run a few hours a day to take the cc down?
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Post a picture of your pool from the outdoors. There is no need for UV in an outdoor pool. With indoor pool, it will help you clear CC. With an indoor pool, I'd take clearing CC over a bit of FC loss.

Be interesting to see your setup. It may be that you get enough UV with the acrylic enclosure, that you don't need it. Or not.

I would experiment. When you smell "chlorine" is not chlorine, it is the chloramines. I would run it enough so that it eliminates the chorine smell. If you have to add a bit more chlorine, so be it!
 

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