Advice on reducing high chlorine levels

[Sephy]

Hello brand new member here.
We have a moderately sized swimming pool, located outside without a cover.

Currently have very high chlorine levels.
This was spotted 8 days ago, and despite not adding any more Chlorine the last 8 days, and having glorious sunshine, the chlorine level doesn’t appear to have dropped.

We’ve recently added about 6-10” of fresh water to the pool but this doesn’t seem to have made any impact.

Just wondering if anyone had any simple solutions before turning to adding some other chemicals to try and bring it down?
Thanks

 

[Jimrahbe]

S,

Without knowing your CYA level, you have no idea if your FC is high or not. The higher the CYA the more FC you need.

Tell us what your CYA (stabilizer) level is..

Thanks,

Jim R.

 

[Mdragger88]

“High” or “low” free chlorine is dependent upon your cya level.
See—>> FC/CYA Levels
It is safe to swim with fc anywhere between minimum & slam level for your cya so long as you can see the bottom of the pool.
Also, test strips are notoriously inaccurate, we recommend using a proper test kit with fas/dpd & cya testing abilities - here’s more info on the ones we recommend & how to obtain them outside of the US

Pool Test Kits - Further Reading

www.troublefreepool.com

 

[Sephy]

Thanks for the advice, I wasn’t aware of the CYA level (it’s not my pool but a family member that I’m temporarily staying with).

Is it possible the CYA level affects an inaccurate FC level on the strips? I do acknowledge they may not be the best or most accurate, however all tests has continually read high (dark purple / 10ppm).

The pool is ever so slightly cloudy but you can clearly see the bottom when near it.

 

[JJ_Tex]

The CYA should not impact the FC reading. Just know that 99% of the time people think they have high chlorine, they do not based on their CYA levels.

Given that you also have slightly cloudy water, which is usually the first signs of algae, I would bet you do not have high chlorine either and possibly have low chlorine if your CYA is high enough.

 

[Sephy]

Ok, I think I’m starting to follow (slowly). If I understand The FC level could be a correct measurement however a high CYA level would allow the CYA to bind to the chlorine and make this less effective?

 

[JJ_Tex]

Ok, I think I’m starting to follow (slowly). If I understand The FC level could be a correct measurement however a high CYA level would allow the CYA to bind to the chlorine and make this less effective?

In a nutshell, yes. Look at the FC/CYA chart in my signature, but your CYA level drives your FC level.

For example, my CYA is 70 and I usually keep my FC around 5-8, but bumped it up to 10 a few weekends ago for a pool party with lots of nasty kids so that I had enough FC to keep the water properly sanitized (sorry, sanitised )

 

[JJ_Tex]

Also note that pucks and other solid forms of chlorine contain chlorine and CYA. The chlorine is used up, but the CYA remains and continues to build up. If they are continual users of pucks, it is not uncommon to see a CYA over 100 which makes it really hard to keep enough FC in the pool even though their FC is "high" per test stips/pool stores who don't use the FC/CYA relationship.

 

[Mdragger88]

You’re understanding correctly
.... "Min FC" is 7.5% of the CYA level
.... "Target FC" is 11.5% of the CYA level
.... "Shock FC" is 40% of the CYA level
So that 10ppm you’re seeing may be high or low without knowing the cya level there’s no telling.

CYA Chlorine Relationship - Further Reading

www.troublefreepool.com

 

[1poolman1]

Hello brand new member here.
We have a moderately sized swimming pool, located outside without a cover.

Currently have very high chlorine levels.
This was spotted 8 days ago, and despite not adding any more Chlorine the last 8 days, and having glorious sunshine, the chlorine level doesn’t appear to have dropped.

We’ve recently added about 6-10” of fresh water to the pool but this doesn’t seem to have made any impact.

Just wondering if anyone had any simple solutions before turning to adding some other chemicals to try and bring it down?
Thanks

View attachment 502622

View attachment 502623

If you have ever spilled or dripped chlorine laundry bleach on you, it is usually at a concentration of 55K-60K PPM (5.5-6%). Will ruin your clothing, to be sure, but does no harm to your person. If you do have 10PPM of free chlorine, that's .00001% chlorine.

 

[PoolStored]

I would question the quality and veracity of the test strips themselves.

Get a decent test kit. Link-->Test Kits Compared

When you have accurate testing, THEN we can talk about your FC levels...

Ok, I think I’m starting to follow (slowly). If I understand The FC level could be a correct measurement however a high CYA level would allow the CYA to bind to the chlorine and make this less effective?

Prime directive: Have enough HOCl (hypochlorous acid) in your pool to kill bacteria and algae. When you add sodium hypochlorite (liquid chlorine, or other chlorine to water, it creates HOCl).

HOCL levels that kill are about .011 for bacteria, and .015 for Algae.

.1 FC with 0 CYA will kill algae and bacteria.
1.3 FC with 30 CYA will kill algae and bacteria.
10 FC with 70 CYA will kill algae and bacteria.

All three have about the same amount of HOCl in the water (+/-).

IT is the FC for your CYA that determines HOCl.

 

[Sephy]

In the interim of getting a decent test kit, I did pickup a strip kit from a local shop that included CYA testing.
I was expecting that to read really high, but intact it appears to be really low:

 

[PoolStored]

Don't trust the guess strips....when does your test kit arrive?

 

[Sephy]

Don't trust the guess strips....when does your test kit arrive?

There isn’t a test kit on order yet. The pool isn’t mine, alas it won’t be something I’ll be investing in myself but will be something I’ll recommend to the owner.
I grabbed the (slightly better than before) test strips while passing the shop earlier due to their low cost.

 

[Sephy]

I really appreciate using strips isn’t great, but any sort of general advice would really be appreciated.
It looks like the water is suffering from low pH and Alkalinity?

 

[PoolStored]

Without a test kit, we really can't help. Kinda' like "first, do no harm." If we don't know where you are at, we can give advice that would do damage or make the situation worse...

 

[JJ_Tex]

Its hard to make adjustments based on test strips, but I'm also confused on your ultimate goal. Are you just trying to get the chlorine down, or are you having other problems?

Most pools need chlorine added daily and will lose 2-4ppm daily so it should come down on its own if you are not adding any. Is this a saltwater pool by chance? Those make their own chlorine so that could explain why your chlorine level is stable without adding any chlorine.

I would still be hesitant to bring the chlorine down since low chlorine is the cause of most pool problems we see here.

 

[Sephy]

Its hard to make adjustments based on test strips, but I'm also confused on your ultimate goal. Are you just trying to get the chlorine down, or are you having other problems?

Most pools need chlorine added daily and will lose 2-4ppm daily so it should come down on its own if you are not adding any. Is this a saltwater pool by chance? Those make their own chlorine so that could explain why your chlorine level is stable without adding any chlorine.

I would still be hesitant to bring the chlorine down since low chlorine is the cause of most pool problems we see here.

Initially I was concerned the chlorine levels were extremely high. Just doing another test now, the levels still seem high (free chlorine), but the pool is looking somewhat coloured and green, not particularly clear.

Looking at this test strip, the pH and Alkalinity appear to be really low, so I guess just some guidance based on the below, if possible?

 

[PoolStored]

Without a test kit, we really can't help. Kinda' like "first, do no harm." If we don't know where you are at, we can give advice that would do damage or make the situation worse...

Link-->Test Kits Compared

 

[BDY]

Colored and green, not clear…. The textbook symptoms of algae and not having enough FC in the pool. You might consider adding 5ppm FC each day until your test kit situation improves.