What is to blame for CC and cloudy water all of a sudden?

[rhawke]

Hi,

After the 28 day startup I had been able to keep the pool quite balanced. I went about 2 weeks without stabilizer (had it ordered online and waiting for it to arrive). The water was so crystal clear that with goggles i could see across the 37 foot pool as if there was no water in it. It looked stunningly clear. This is what it tested as during those 2 weeks

FC: 0.5 to 1.5 ppm
CC: barely changed color when adding the R0003 - probably 0.1 or 0.2
Calcium: 325
PH: adjusted every 5-7 days from 7.8 back down to 7.4
TA: 70-80
CYA: around 10-20 from some tri chlor pucks the PB used during the startup
Salt: 3600

Then I added a 4 lb of stabilizer, separated in 2 doses over 3 days which got the pool to CYA to around 60. I didn't want to go higher yet, just in case I needed to shock. I manually incrase the FC to 4.0 one time and then over the next week adjusted the SWG to maintain approx 3-4 FC.

This was 3 weeks ago and since then we have had quite a bit of rain, I had to drain the pool by 1-2 inches twice. There has also been quite a bit of organic matter that blew into the pool (dirt, sand, leaves, mulch). The water still looks great when you are looking at it from above, but with goggles underwater, I have lost that exceptional clarity.

Here are my test min/max from the past 2 weeks

FC: 3-4 ppm
CC: always measures at 0.5 but the color is now much darker when i add the R0003 - there is also a slight chlorine smell after swimming
Calcium: dropped by 25 each week down to 275 (due to draining)
PH: adjusted every 5-7 days from 7.8 back down to 7.4
TA: 70
CYA: 50
Salt: 3200 (dropped due to draining the pool)


My main question: Is this mainly a problem of all the rain and organic matter that blew into the pool plus the rain water? Or did I mess up the balance by adding the Stabilizer and should have aimed for a higher FC?

What is the best way to get my water as clear as it was again and get rid of the CC which leaves the very light chlorine smell on our skin after swimming?

 

[kimkats]

My guess is you caught something before it happened all of the way. If you want you can do the OCLT as seen here: Pool School - Perform the Overnight FC Loss Test (OCLT) (make sure the SWG is off if you do this)

Me? I would raise my FC to SLAM level using liquid chlorine and keep it there for a couple of days. Keeping the pump on the whole time to get what ever it is up and out.

Kim

 

[domct203]

Hi,

After the 28 day startup I had been able to keep the pool quite balanced. I went about 2 weeks without stabilizer (had it ordered online and waiting for it to arrive). The water was so crystal clear that with goggles i could see across the 37 foot pool as if there was no water in it. It looked stunningly clear. This is what it tested as during those 2 weeks

FC: 0.5 to 1.5 ppm
CC: barely changed color when adding the R0003 - probably 0.1 or 0.2
Calcium: 325
PH: adjusted every 5-7 days from 7.8 back down to 7.4
TA: 70-80
CYA: around 10-20 from some tri chlor pucks the PB used during the startup
Salt: 3600

Then I added a 4 lb of stabilizer, separated in 2 doses over 3 days which got the pool to CYA to around 60. I didn't want to go higher yet, just in case I needed to shock. I manually incrase the FC to 4.0 one time and then over the next week adjusted the SWG to maintain approx 3-4 FC.

This was 3 weeks ago and since then we have had quite a bit of rain, I had to drain the pool by 1-2 inches twice. There has also been quite a bit of organic matter that blew into the pool (dirt, sand, leaves, mulch). The water still looks great when you are looking at it from above, but with goggles underwater, I have lost that exceptional clarity.

Here are my test min/max from the past 2 weeks

FC: 3-4 ppm
CC: always measures at 0.5 but the color is now much darker when i add the R0003 - there is also a slight chlorine smell after swimming
Calcium: dropped by 25 each week down to 275 (due to draining)
PH: adjusted every 5-7 days from 7.8 back down to 7.4
TA: 70
CYA: 50
Salt: 3200 (dropped due to draining the pool)


My main question: Is this mainly a problem of all the rain and organic matter that blew into the pool plus the rain water? Or did I mess up the balance by adding the Stabilizer and should have aimed for a higher FC?

What is the best way to get my water as clear as it was again and get rid of the CC which leaves the very light chlorine smell on our skin after swimming?

Maintaining a FC of 3ppm is right on the minimum recommend. If your FC has dipped below minimum between SWG cycles, algae could start growing.

A proper SLAM Process will bring back that clear water.

Are you doing the CYA test outside on a bright sunny day, with the sun to your back, reading the view tube in your shadow at waist level?

 

[rhawke]

Maintaining a FC of 3ppm is right on the minimum recommend. If your FC has dipped below minimum between SWG cycles, algae could start growing.

A proper SLAM Process will bring back that clear water.

Are you doing the CYA test outside on a bright sunny day, with the sun to your back, reading the view tube in your shadow at waist level?

Yes regarding the cya testing, but to be fair I am never quite sure when the black dot is really disappearing because the white sticker on the tube creates a shadow that also looks like a bigger dot at the bottom. But just based on the pool math app it should be close.

The thing is that the pool looks sparkling from the outside and I have not seen any sign of algae like slimy walls or some spots with green. And when you look into the water 5 to 6 feet down with goggles it looks crystal clear as well. It just Vision after 20pluw feet that gets cloudy...

I just realized we also have barely had any sun the past three weeks, is that why the cc are increasing and not going away?

I will change my swg to maintain 4ppm for now.

 

[domct203]

Algae spores are microscopic, by the time you see green there’s millions of them.

A cloudy day can give the water a dull look as well.

If this were my pool I would raise my FC to about 15% of CYA (8-10ppm) and do an OCLT. If I barely passed or failed I would SLAM at first opportunity, it should go quick if there is no green at all, anywhere (back of weir door, light niche, etc).

 

[rhawke]

Algae spores are microscopic, by the time you see green there’s millions of them.

A cloudy day can give the water a dull look as well.

If this were my pool I would raise my FC to about 15% of CYA (8-10ppm) and do an OCLT. If I barely passed or failed I would SLAM at first opportunity, it should go quick if there is no green at all, anywhere (back of weir door, light niche, etc).

Thanks, my wife is pregnant and she really loves to swim daily as it helps her feel better which is why I am reluctant to do a SLAM.

Do I really need to raise the FC that much? Without stabilizer I was fine with 0.5 to 1.5 ppm. I don't want to raise the FC to a level where it may affect my wife's health. She also has very sensitive skin and gets rashes at public pools all the time.

 

[ajw22]

As you raise the CYA you raise the FC because most of the FC gets bound with the CYA. With higher CYA and FC at [FC/CYA][/FC/CYA] levels the actual available CL is your .5 - 1.5 ppm. This is the way the FC/CYA chart was designed to maintain the same available CL as CYA levels rise. If you want the chemistry behind this there are treads about the FC/CYA relationship in the The Deep End...

The actual discussion about FC vs. available CL vs CC and it's relationship to CYA level is more complicated than the simple concepts in Pool School.

You would be shocked at the chemical balance in public pools. The chemistry will be very different than the TFP Pool School - Recommended Levels

 

[jblizzle]

Swimming in a pool with the FC at the shock level for your CYA ([FC/CYA][/FC/CYA]) actually has less active chlorine (harshness) than you would find in a public pool with a 1ppm FC and 0 CYA. Often irritation is due to higher CC and not enough chlorine.

Bottom line, follow the SLAM Process process which will likely only be a day or 2. And your wife is perfectly safe to swim while you are at it.

 

[domct203]

Thanks, my wife is pregnant and she really loves to swim daily as it helps her feel better which is why I am reluctant to do a SLAM.

As the algae spores multiply, they will quickly deplete that low FC. Do you really want to take that chance? Algae is a green plant, it’s just a nuisance and doesn’t pose a health risk. However, the bacteria/viruses that could start to grow from bird/animal droppings entering a stressed sanitation system is a different story.

I would raise CYA to 30ppm and SLAM. You do have a FAS/DPD chlorine test, correct? It should go quick.

At the least do the OCLT to confirm/dismiss the start of an algae bloom.

 

[rhawke]

I would raise CYA to 30ppm and SLAM. You do have a FAS/DPD chlorine test, correct? It should go quick.
At the least do the OCLT to confirm/dismiss the start of an algae bloom.

I already have 50ppm for CYA at this point. I was just referencing the time before I added the stabilizer.

I will to the OCLT tonight and report back tomorrow.

As you raise the CYA you raise the FC because most of the FC gets bound with the CYA. With higher CYA and FC at [FC/CYA][/FC/CYA] levels the actual available CL is your .5 - 1.5 ppm. This is the way the FC/CYA chart was designed to maintain the same available CL as CYA levels rise. If you want the chemistry behind this there are treads about the FC/CYA relationship in the The Deep End...

Swimming in a pool with the FC at the shock level for your CYA ([FC/CYA][/FC/CYA]) actually has less active chlorine (harshness) than you would find in a public pool with a 1ppm FC and 0 CYA. Often irritation is due to higher CC and not enough chlorine.

So does this means only the FC that is not bound to CYA will have an effect on the skin? I understand how it works for the pool, but I wasn't sure if for the human body the FC counts as tested (e.g. 5 ppm) or if it is only the FC that is truly available unbound from the CYA?

 

[jblizzle]

So does this means only the FC that is not bound to CYA will have an effect on the skin? I understand how it works for the pool, but I wasn't sure if for the human body the FC counts as tested (e.g. 5 ppm) or if it is only the FC that is truly available unbound from the CYA?

Basically, it is only the "unbound" chlorine that impacts the skin ... although again the skin is more impacted by CCs than by chlorine itself. Often very high chlorine level baths are recommended to treat some skin conditions.

You can check of this table and see the active chlorine levels (aka "harshness") as a function of CYA and FC:
http://troublefreepool.com/~richardfalk/pool/HOCl.htm
Ignore the colors ... I am not sure what they are intended to represent.

 

[rhawke]

Thanks that is very interesting!

Do you have an explanation why with no CYA the true FC is still only about half of what is tested?

Looking at the colors, it looks like the red area is considered "too low" the green area is considered "ideal" and the blue area is "higher than necessary". It somewhat lines up that way with the FC / CYA chart.

 

[jblizzle]

I do not have a explanation for the value being half. I am sure I have read it, but it is likely buried in the Deep End forum. Perhaps something related to the 2 chlorine atoms in Cl2?

I think you color idea is close but not exactly, can't remember if it is related to likelihood of algae of kill times for pathogens.

 

[rhawke]

Ok I did the OCLT. I was distracted this morning and didn't take the morning reading until 10:00am but it has been a cloudy day so far. The chlorine went from 4.0 last night at 9pm to 3.5 this morning at 10:00am which is a loss of 0.5 ppm. Typically i have the SWG run for a bit at night too so it probably wouldn't drop that much.

Per the OCLT instructions a SLAM should be done if the loss is 1 ppm or more.

I also noticed that the CC still measures at 0.5 but the pink color is much fainter than it was 2 days ago.

So I guess based on this I should just keep the FC at 4 or 5 ppm for now and see where that gets me? Or should I still do a SLAM?

 

[mknauss]

Did you have the SWCG off over night?

 

[jblizzle]

I prefer the OCLT be done at a higher FC (10ppm +), although that point seems to raise some debate.
Also, if the SWG was not off, then it was not a valid OCLT.

 

[rhawke]

Yes I did set the swg at 0 percent for the night.

 

[ajw22]

I think you are just seeing the limits of your cartridge filter. I would keep your FC at 4 - 5 and do normal monitoring of the pool.

 

[kimkats]

What he ^^^^^^^^^^^ said!

 

[rhawke]

I think you are just seeing the limits of your cartridge filter. I would keep your FC at 4 - 5 and do normal monitoring of the pool.

That would be a bummer if the filter can get the water as clean as it was before.

Would adding one of those pool clarifiers help? My father in law uses that whenever his pool is slightly cloudy. He said it binds particles that are too small for the filter and clumps them together so that the filter can catch them. I've seen it work in his pool but I haven't seen anybody here at TFP recommend it?