Chasing CSI on the pool app

[Jamestown]

14500 gal. Salt water pebble pool

Why does the formula for an ideal CSI include a range for ph and alkalinity that is outside their respective upper limits?

If I was not chasing CSI, I would add muriatic acid to the pool based on pH reading. Even a pH of 7.6 pushes the CSI outside the range. What is the most important element to maintain overall chemistry and prevent etching or corrosion?

pH=8.0
Total Alk= 100
CH= 360
Stabilizer = 70
CSI = - 0.09
Water temp =34 deg

 

[JamesW]

The CSI is most important.

The pH can be anywhere from about 7.2 to 8.3.

Low pH (Below 7.2) can cause copper corrosion.

If the pH is kept at more than 7.9, it can be difficult to measure with the drop test unless you know what those colors look like.

If the pH is kept at 8.0 to 8.3, I would recommend a pH meter to be sure.

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[Jamestown]

Thanks James but that doesn’t really address the conundrum. I’ve been adding chemicals based on Ph and TA now to learn that an ideal Ph and TA can yield a CSI outside the range. That’s counterintuitive.

 

[Jamestown]

The CSI is most important based on the experts. A low ph can yield a CSI that leads to corrosion. Calcium hardness is amother factor - can’t look at these individual chemistries in isolation.

 

[PoolStored]

A low ph can yield a CSI that leads to corrosion.

So we are clear for our members, now and in the future, this is plaster corrosion. Low CSI does not mean it is corrosive to metals. CSI does not measure metal corrosion.

Low CSI is typical in the winter with colder waters..nothing needs to be done about low CSI in the winter...

CSI and LSI - Further Reading

www.troublefreepool.com

 

[JamesW]

The pH can be anywhere from about 7.2 to 8.3.

The TA can be anywhere from about 50 to 120.

Don't chase "Ideal" levels for pH and TA.

In fact, don't adjust the pH at all unless it is outside of about 7.2 to 8.3.

In my opinion, the pH works better at the highest levels.

The TA is right when the pH is stable.

Keep the CSI between about -0.3 and 0.0.

If the CSI is good, leave the pH and TA alone.

It can be confusing, but you will get used to it.

 

[Newdude]

I’ve been adding chemicals based on Ph and TA now to learn that an ideal Ph and TA can yield a CSI outside the range.

There are too many possibilities to cover them all. Way, way, way too many possibilities.

 

[Jamestown]

The pH can be anywhere from about 7.2 to 8.3.

The TA can be anywhere from about 50 to 120.

Don't chase "Ideal" levels for pH and TA.

In fact, don't adjust the pH at all unless it is outside of about 7.2 to 8.3.

In my opinion, the pH works better at the highest levels.

The TA is right when the pH is stable.

Keep the CSI between about -0.3 and 0.0.

If the CSI is good, leave the pH and TA alone.

It can be confusing, but you will get used to it.

add a ph of 7.2 and and TA of 60 to pool math and you’ll need a very high calcium to achieve a slightly negative CSI. (Which is my goal)

In cold water / months, you need a higher ph and TA to stabilize CSI.

 

[Jamestown]

So we are clear for our members, now and in the future, this is plaster corrosion. Low CSI does not mean it is corrosive to metals. CSI does not measure metal corrosion.

Low CSI is typical in the winter with colder waters..nothing needs to be done about low CSI in the winter...

CSI and LSI - Further Reading

www.troublefreepool.com

Then why does pool math include a temp input that affects the CSI reading ?

So I’ve been chasing a CSI by adding chemicals that were already in the normal range now to learn this is obsolete in winter months??

 

[PoolStored]

In the winter, as the temperature goes down, the PH naturally goes up, resulting in the CSI staying at about the same level it starts with. If you are tracking and adjusting PH, you should allow this natural PH increase instead of "correcting" it.

Ignore the CSI in the winter.

Keep your CSI in range about 9 months out of the year and your pool will be fine.

 

[ajw22]

Plaster does not corrode.

Low CSI can cause etching of plaster.

High CSI can cause scaling.

We accept low CSI in the winter cold water. 3 to 4 months of low CSI does not do much damage.

 

[PoolStored]

Why are you trying to drive pH so low? With a TA of 60, your pH should be pretty stable in the higher 7s - 8.0.

 

[Jamestown]

Why are you trying to drive pH so low? With a TA of 60, your pH should be pretty stable in the higher 7s - 8.0.

I’m not

I just want my CSI to stabilize around -0.3 and that’s not possible unless my ph is > 7.8 and TA 80-90 in the winter. But then I read on here that CSI is not that important in the winter months with pool temps in the 30s.

 

[Newdude]

But then I read on here that CSI is not that important in the winter months with pool temps in the 30s.

Most of the country can't mess with theirs right now and will get by just fine. Up north it might be sitting for 6 more months. So we relaxed a little on how important it was for the few who could still mess with theirs mid winter.