PH, alkalinity, and Cyan

[Jonhood]

2 questions -
Pool is nearing 4 months old
1. Add alkalinity up to get to 75 PPM - PH increases to 8 or above. Add muriatic acid to get back in PH range - alkalinity drops out of range - will this ever equal out - I feel like a dog chasing his tail!
2. Why is Cyanuric acid needed with a SWG as it makes chlorine when it’s running.
Thank you,
Jon Hood

 

[Newdude]

1. Add alkalinity up to get to 75 PPM - PH increases to 8 or above. Add muriatic acid to get back in PH range - alkalinity drops out of range - will this ever equal out - I feel like a dog chasing his tail!

Yes, but it might be a while. New plaster can have a MA appetite for 6 to 12 months.

Any aeration makes it worse so try to limit your water features to running 2 times a day, just long enough to exchange the water, when they don't need to be used. If you're out there enjoying them, great. Enjoy them. When you go back inside, to bed, etc, turn them off.

Why is Cyanuric acid needed with a SWG as it makes chlorine when it’s running

CYA buffers the chlorine so it takes longer to burn off in the sun. Without CYA, your chlorine would be gone in no time.

The CYA level for a salt pool is higher because the unit produces FC so slowly. It's like standing there adding one drop at a time, spreading the 1 gallon dose over 12+ hours. With a liquid chlorone dosed CYA level, it typically burns off faster than it's produced. So SWG pools use a higher CYA level to accommodate that.

 

[Jonhood]

Yes, but it might be a while. New plaster can have a MA appetite for 6 to 12 months.

Any aeration makes it worse so try to limit your water features to running 2 times a day, just long enough to exchange the water, when they don't need to be used. If you're out there enjoying them, great. Enjoy them. When you go back inside, to bed, etc, turn them off.

CYA buffers the chlorine so it takes longer to burn off in the sun. Without CYA, your chlorine would be gone in no time.

The CYA level for a salt pool is higher because the unit produces FC so slowly. It's like standing there adding one drop at a time, spreading the 1 gallon dose over 12+ hours. With a liquid chlorone dosed CYA level, it typically burns off faster than it's produced. So SWG pools use a higher CYA level to accommodate that.

Ok but right now I have a FC of 10PPM, CYA is at 40 PPM , SWG is set at 20% - I test frequently late in the afternoon and live in SUNNY SW FLORIDA!

 

[Mdragger88]

Try letting ta fall to 50 before increasing to 60 or so with baking soda
Aim for ph of mid to high 7’s when dosing with acid. Some pools will ride at 7.8 for quite some time. Dropping ph in the low 7’s won’t really buy you anymore time between doses but big swings will lower your ta & contribute to the ride you’re on.
As the plaster cures the merry go round will get better but you will still likely always need to use acid.
Like @Newdude said, adjusting your water features can also help tremendously.

 

[Mdragger88]

Lower your setting to 10%,
How long are you running your pump?

 

[Mdragger88]

Is your pool covered?

 

[Jonhood]

Lower your setting to 10%,
How long are you running your pump?

10 hrs a day right now - but pulling back to 8 this weekend - days are getting shorter

 

[Jonhood]

Is your pool covered?

No

 

[Jonhood]

No

Well - it is covered with a pool screen

 

[Newdude]

Well - it is covered with a pool screen

That helps a good deal and is likely the reason you are overproducing in south FL with a low CYA. Having an almost 3X SWG isn't hurting either.

 

[Mdragger88]

As the uv & temp lessens the fc demand decreases. Average residential pools use approximately 1-4 ppm/day depending upon the time of season.
Here’s roughly what you’re producing now per day with your current settings


When you turn it down/lower the run time be sure to keep an eye on it. A high uv/warm spell can catch you off guard.
Be sure to stay above minimum FC/CYA Levels
If the water temp drops below 52 degrees the swg will no longer produce fc & you will need to manually chlorinate.
The cya of 40 is probably ok for now - through the winter but during the summer at least 60/70 will be better.
The more you protect the fc from the sun —> the less fc your swg will need to produce —> the longer the cell will last.
All swg cells have a finite lifespan (ichlor lists 10k hrs @ 100%)

 

[pjt]

alkalinity drops out of range

What TA are you targeting? A TA of 50 is perfectly fine. Stop adding baking soda. Let the TA slowly drift down as you add MA for pH control. Your TA and pH will settle where they're happy.

Taylor’s Complete pool care DPD test kit

What model # is your kit?