Should I bring Chlorine to 10 ppm to be safe?

[swimmynoodle]

Hello all!

Fine tuning the chemicals for my swim spa, I have two quick questions.
1. I found this old TFP post from 2008:

SO, what's a good TA then? Because spas tend to have a lot of aeration from jets and because the water is hot, it is best to keep the TA low at around 50 ppm.

How do I use Chlorine in my Spa or Hot Tub?

..many other posts (and instructions on my chemicals) say to have hot tub TA around 150 ppm. Any thoughts on this? 50 ppm seems really low and I would like to understand the reason.


2. The chemicals in my swim spa are all balanced now. I ran the big blue bottle of AhhSome through it 32 times until no gunk came out. As a safety precaution, is it a 'thing' to bring chlorine levels to 10ppm for a couple of days just to be sure the jets, hoses, etc are sanitized? The previous owners didn't take care of it and although it is sparkling clean and now looks like new with a FC level of 3 ppm, I want to be sure its safe for me and my family and the thought of swimming in it, knowing what it looked like before I cleaned it, grosses me out.

Thank you.

 

[JoeSelf]

Post a full set of results from your test kit.
FC
CC
PH
CH
TA
CYA

CYA buffers the FC and they go hand in hand. FC level depends on CYA. See
FC/CYA Levels.

Did you have any FC while you were purging?

Lower TA keeps the PH from rising fast.

 

[Mdragger88]

So long as the water is crystal clear and cc’s or 0.5 or less there’s no reason to maintain slam fc level for an extended period of time after purging.

As for the ta -
We recommend switching from acidic dichlor to liquid chlorine after cya is in the 30’s so there’s no need to attempt to maintain such a high ta.
Attempting to do so will have you on a merry go round with acid & baking soda additions as a higher ta results in faster ph rise which is already an issue in such an aerated environment.
So long as ta is 50 or above there’s no need to increase it. The lower ta harms nothing.
Many manufacturers/retailers assume you will be using acidic chlorine products (dichlor/frog) for daily chlorination or mps regularly (because they sell them alongside the spas) which can tank your ph & ta so they sure their bets with the higher recommendations. They also wish to sell you expensive ph & ta up.

 

[phonedave]

TA and pH come to an understanding between the two of them. If you try and drive to BOTH an "ideal" pH and TA you will pull your hair out, because as you adjust one, the other will change.

When I change my hot tub water, I check pH on a daily basis and add acid as necessary to keep it in the 7.4 area. After about a week, it no longer requires daily adjustment and the pH tends to be pretty much stable. Whatever the TA happens to be at that point is where it stays.

 

[Mdragger88]

I do similar to phonedave - the dichlor additions at the beginning lower ph each time leaving me with a few acid additions later on to get ph /ta down.
After about a week I end up with ta in 50/60 range and very few acid additions going forward if ph goes above 8. My fill water ta is about 100-110 usually. I also usually add boric acid once ta is 50/60.
I use dichlor occasionally to keep cya topped up so I am mindful of its effects on ph and can forego acid when I use it.

 

[swimmynoodle]

Hi everyone, thanks for the replies. The results are in:
(Tested with Taylor K-2006)
FC 2
TC 2
CC 0
PH 8
TA 130 ppm
CYA 0
CH 60 ppm

So clearly, as a self-designated Pool-Newbie®, my numbers aren't that great. But, I'm taking everyone's advice, researching, and learning.

The Newbie Chemicals I bought (before finding this forum) are seen in the attached pictures. The stuff to the right of the line I did not use.

Correct me if I am wrong but from my research in TFP the following needs to change:
1. I need to get my CYA up to 30 ppm with dichlor and then switch to liquid chlorine to keep CYA levels from spiking.
1a. Do I need CYA levels so high seeing the swim spa is covered 99.9% of the time?
2. I should stop using the junk Clorox shock and buy straight dichlor.
3. I need to lower my TA because it keeps spiking my pH.

Things my Pool-Newbie® brain cannot figure out:
1. How do I lower TA? Seeing there is no such thing as TA decreaser, should I bring TA down by bringing my pH down and then aerate to bring pH up to correct levels?
2. The problem with aeration is my swim spa has a timer that turns off the jets after 15 minutes. I would have to go down every 15 minutes for however long to keep them running.
3. What is 'straight dichlor'? Buy it at a pool store?
4. I guess what myself and many newbies experience is the constant fluctuations between pH and TA.
5. Should I add boric acid to help stabilize pH?
6. I don't get how my CYA can be 0.00 if I added dichlor to it. I feel if I have to add more dichlor to the pool to get CYA up to 30, my FC levels are going to be 500,000 ppm.

Mama mia this is complex Thank you for all of your help!

@JoeSelf @Mdragger88 @phonedave

 

[JoeSelf]

Lowering PH will bring the TA down. Yes you have to do multiple rounds of running the jets. Add acid to lower PH down to 7.2ish. run jets until your back up to 8.0 and then add acid again. You can chose to do this all at once or over time. You will find a level where your PH will stay stable. Adding borax before PH is stable will make bringing down TA harder and require larger doses of acid.

This is what I use for dichlor. See the difference in percentage. What you haveb8s not the same.

 

[Mdragger88]

Hi everyone, thanks for the replies. The results are in:
(Tested with Taylor K-2006)
FC 2
TC 2
CC 0
PH 8
TA 130 ppm
CYA 0
CH 60 ppm

So clearly, as a self-designated Pool-Newbie®, my numbers aren't that great. But, I'm taking everyone's advice, researching, and learning.

The Newbie Chemicals I bought (before finding this forum) are seen in the attached pictures. The stuff to the right of the line I did not use.

Correct me if I am wrong but from my research in TFP the following needs to change:
1. I need to get my CYA up to 30 ppm with dichlor and then switch to liquid chlorine to keep CYA levels from spiking.
1a. Do I need CYA levels so high seeing the swim spa is covered 99.9% of the time?

Yes - having cya in the 30ppm range allows you to keep fc at sanitary levels at all times without being too harsh on people & your expensive equipment (head rests, cover, ss jets, etc.)

2. I should stop using the junk Clorox shock and buy straight dichlor.

Yes- it has copper in it. The copper doesn’t leave & can cause staining when the level gets high enough. Its also not 99% dichlor so it makes it hard to properly calculate with PoolMath
I buy my 99% dichlor at Walmart for $20 - i have a small tub and 1# lasts me at least a year - the 2.25# should last you a while

3. I need to lower my TA because it keeps spiking my pH.

Things my Pool-Newbie® brain cannot figure out:
1. How do I lower TA? Seeing there is no such thing as TA decreaser, should I bring TA down by bringing my pH down and then aerate to bring pH up to correct levels?
2. The problem with aeration is my swim spa has a timer that turns off the jets after 15 minutes. I would have to go down every 15 minutes for however long to keep them running.

See if it’s possible to change that setting- mine does 30 minutes. Otherwise yes, thats what you’ll need to do.
The good news is that change happens quickly in a small body of water with lots of aeration so just actively work on it when u have the time. Otherwise, just managing ph will bring down the ta over time.

3. What is 'straight dichlor'? Buy it at a pool store?

See above response

4. I guess what myself and many newbies experience is the constant fluctuations between pH and TA.
5. Should I add boric acid to help stabilize pH?

Yes, but AFTER you get ta down to the 50/60 range because once borates are in the mix it requires more acid to do the same job when ph needs to be lowered.

6. I don't get how my CYA can be 0.00 if I added dichlor to it. I feel if I have to add more dichlor to the pool to get CYA up to 30, my FC levels are going to be 500,000 ppm.

Use poolmath effects of adding to calculate- 99% dichlor adds approximately 1ppm cya for every 1ppm of fc.
so essentially, raising fc to 10ppm 3x’s from zero would do the trick (although i don’t recommend letting fc go to zero. So say adding 5ppm 6x’s.
As mentioned it’s acidic (use effects of adding) so take that into consideration before also adding acid to lower ph.

Mama mia this is complex Thank you for all of your help!

@JoeSelf @Mdragger88 @phonedave

 

[JoeSelf]

To get CYA to 30 you add the dichlor when needed as your sanitizer and oxidizer. Use effects of adding in poolmath to see what each dichlor dose adds for CYA. After dosing add that to your previous total. I do this in a single test.

You won't be able to see your first doses in a test because the test only goes down to 20. At least on my tube it does. It's old. Been here a long time.

 

[Mdragger88]