- Mar 5, 2020
- 3,056
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
1)
Don't think there's much to add to what's been said before.
2)
As said before, SLAM-FC is 40% of the CYA. At this FC/CYA ratio there is a HOCl concentration of about 0.32ppm in the water. This is roughly equivalent to FC of 0.64ppm without CYA in the water (at pH 7.5 you would then have 0.32ppm HOCl and 0.32 ppm OCl-).
There is no magic to this number, it's just an empirically proven compromise between fast enough algae kill rate, FC loss to UV-light, and harshness of chlorine to equipment and bathers.
3)
Also not much to add. Maybe only to clarify why high TA accelerates pH-rise, which is a bit counterintuitive at first sight with TA also buffering pH.
TA consists mainly of dissolved carbonates. Carbonates mean that there is also dissolved CO2 in the water, and a lot more than there would be naturally in water. It's basically an oversized soda bottle without the lid on. The CO2 bubbles out, which in the case of a sweet soft drink doesn't just make it flat, but also taste even sweeter because it became less acidic - which means that pH increased.
The same thing happens in a pool: CO2 outgasses and drives pH up in the process.
When there is no "acidic pressure" from using Trichlor pucks, TA doesn't need to be as high to have enough buffering, and lowering TA will result in more stable pH.
4)
The chemical reactions of releasing chlorine from CYA and attaching it are both happening all the time. The reaction rates depend on the availability of reaction partners. At same concentrations of attached and not-attached chlorine, the attaching reaction is faster than the releasing reaction (and even more so when you start with only not-attached chlorine). That means in a certain time interval more chlorine attaches to CYA than gets released. Therefore, you will now have more chlorine attached to CYA than not-attached. The attaching reaction rate will consequently slow down and the releasing one will speed up, until you reach an equilibrium where both reactions happen at the same rate, and concentrations appear constant for the outside observer - we have reached an equilibrium. This equilibrium is established very fast. But this a dynamic equilibrium, if you could make a slow motion movie, you would see chlorine attaching to CYA and getting released the whole time, but equally fast.
As soon as some not-attached chlorine gets removed from the equation by killing something (turning into chloride in the process), the equilibrium is disturbed, and the releasing reaction rate will be slightly faster than the attaching reaction, until a new equilibrium is established. Very fast again. Simply speaking, some chlorine got released from the reservoir.
Don't think there's much to add to what's been said before.
2)
As said before, SLAM-FC is 40% of the CYA. At this FC/CYA ratio there is a HOCl concentration of about 0.32ppm in the water. This is roughly equivalent to FC of 0.64ppm without CYA in the water (at pH 7.5 you would then have 0.32ppm HOCl and 0.32 ppm OCl-).
There is no magic to this number, it's just an empirically proven compromise between fast enough algae kill rate, FC loss to UV-light, and harshness of chlorine to equipment and bathers.
3)
Also not much to add. Maybe only to clarify why high TA accelerates pH-rise, which is a bit counterintuitive at first sight with TA also buffering pH.
TA consists mainly of dissolved carbonates. Carbonates mean that there is also dissolved CO2 in the water, and a lot more than there would be naturally in water. It's basically an oversized soda bottle without the lid on. The CO2 bubbles out, which in the case of a sweet soft drink doesn't just make it flat, but also taste even sweeter because it became less acidic - which means that pH increased.
The same thing happens in a pool: CO2 outgasses and drives pH up in the process.
When there is no "acidic pressure" from using Trichlor pucks, TA doesn't need to be as high to have enough buffering, and lowering TA will result in more stable pH.
4)
The chemical reactions of releasing chlorine from CYA and attaching it are both happening all the time. The reaction rates depend on the availability of reaction partners. At same concentrations of attached and not-attached chlorine, the attaching reaction is faster than the releasing reaction (and even more so when you start with only not-attached chlorine). That means in a certain time interval more chlorine attaches to CYA than gets released. Therefore, you will now have more chlorine attached to CYA than not-attached. The attaching reaction rate will consequently slow down and the releasing one will speed up, until you reach an equilibrium where both reactions happen at the same rate, and concentrations appear constant for the outside observer - we have reached an equilibrium. This equilibrium is established very fast. But this a dynamic equilibrium, if you could make a slow motion movie, you would see chlorine attaching to CYA and getting released the whole time, but equally fast.
As soon as some not-attached chlorine gets removed from the equation by killing something (turning into chloride in the process), the equilibrium is disturbed, and the releasing reaction rate will be slightly faster than the attaching reaction, until a new equilibrium is established. Very fast again. Simply speaking, some chlorine got released from the reservoir.