Saturation index high

[Tomk2]

Hello - google has failed to answer my questions about high pH despite low TA, and then there is the saturation index.

I live in the Phoenix area, and I am always fighting elevated pH. The water teperatures are high this time of year, around 85 degrees. The air temperature is over 100 degrees, intense sunlight. Pool is pebble tech. Draining a pool this time of year is inadvisable due to the risk of cracking.

The water is crystal clear, so I am kind of treating numbers and not problems. The pH will drift up to 7.8 and higher if I do nothing. If I add muriatic acid, it comes down for a day at most when my total alkalinity is 90 or higher. If my TA is 70 or 80, the pH will stay below 7.8 for 2 or three days after adding acid.The only time my pH dropped below 7.2 was when my TA was in the 50 to 60 range after adding acid.

With the pH around 7.8, TA 80, water temps 85, CYA around 30, Calcium hardness at 350, my saturation index is above 0.3
If I keep adding muriatic acid to get the pH down to 7.6, the TA will go down to 70, yet the pH still creeps up after a few days. It seems that if I keep adding acid to lower the pH I am going to also lower TA to the point that the pH may drop too low?

So I wonder, with clear water, perhaps it is better to let the pH drift up to the 7.8 range, leave the TA in the 70 - 80 range, and just let the saturation index be in the 0.3 to 0.4 range? If not, then I add baking soda one day, then add acid for a week or two, and repeat.

Chlorination is with liquid chlorine unless I am not going to be able to do the pool care, then some trichlor pucks until I am able to resume. Chlorine tests in the 0.5 to 4.0 range, most common daily result is 3.

 

[Texas Splash]

Welcome to TFP! You can let the TA fall even more. Let is drop around 50 - 60 to slow your rate of pH increases. You really need to control that pH and keep it no higher than 7.8 in your area (scale). Actually, I'm astonished your CH is only 350. Are you using a water softener to top-off the pool? How are you testing your water?

As for your FC, refer to our FC/CYA Levels. Confirm your CYA and that will determine your ideal FC ratio to avoid algae.

You'll see this any many more great articles on our Pool Care Basics page. Hope that helps. Enjoy the forum.

 

[Tomk2]

No water softener, municipal supply mostly from the Colorado River and Salt River via canals/aqueducts, perhaps some groundwater. I use TF pro test kit. The pool is almost 30 years old, I just started taking care of it last year. Some scaling from years of previous owners just tossing in Tricolor pucks and no other chemistry care. I figured the only way to keep my pH in the 7.6 to 7.8 range was to let the TA fall, but all the internet "wisdom" (if you can call it that) says to keep it higher. I suppose the 3 or 4 monsoon storms over the summer that raise my pool water level 6 inches in an hour (yeah, that happens) might have a dramatic effect, I will just backwash out the surplus and re-test when that happens.

I usually add the chlorine at night, then test the next evening. If it is between 1 to 4 after a day of intense sunlight, I add about the same amount.
Does anyone live somewhere the water is not hard and with a high pH? LOL.

 

[Oly]

Getting your TA to 50-60ppm will slow your pH rise and lower your CSI as will keeping your pH in the low 7s if possible. Test your fill water for TA and CH to anticipate effects of adding water. Don't be in a rush to add sodium bicarbonate when your TA is above 50ppm especially if your fill water is high in TA.

 

[Mdragger88]

You are loosing alot of fc to the sun in your location- you may need to increase cya to 40-50 to help. No matter the cya you must dose high enough that your fc doesn’t fall below minimum before the next test/dose or nasties will grow.
Dosing to high target or a scootch higher is good insurance.
FC/CYA Levels
Before raising cya do an
Overnight Chlorine Loss Test to be sure nothing is brewing due to your dipping below minimum on a regular basis.
Increasing cya will also lower csi some.

 

[pjt]

I add baking soda one day, then add acid for a week or two, and repeat.

Stop adding baking soda.

You're chasing your tail with baking soda and MA additions. As you manage pH, allow the TA to decrease to 50-60. A TA of 50 (don't go lower) is perfectly fine and will result in minimal to no pH rise. Pool should require minimal to no MA at that point and pH will likely stabilize in the high 7s, which is great.

Chlorine tests in the 0.5 to 4.0 range, most common daily result is 3.

Your FC is too low, which risks big problems. Focus on fixing this first. Chlorine is king. Follow the FC/CYA chart:

CYA around 30

Your CYA is too low for Phoenix. Bump it up to 50-60.

What's the TA and CH of your fill water?

 

[Tomk2]

When I took over the pool, the CYA was over 150. It took me over a year to bring it down. Interestingly, last November it was 90, and this May it was under thirty (pool store said it was 8, my kit had a lower test level of 30). That was a surprise, considering it didn't change much all summer and I ignored the level all winter.

The fill water (today) has: TA 130 and a CH of 200.

Yes, I knew the Baking soda was raising TA and pH, and the muriatic acid was lowering TA and pH. The issue was just how low to keep the TA so that the pH was what I wanted. I could not find a single reference for keeping the TA lower than 70 or 80 in any of the easily searched pool care sites. Yet at right around a TA of 70 to 80 the pH seemed to stay at or below my target of 7.6 longer, but never stay there. I had experimented with TA between 70 and 90 by using baking soda and muriatic acid, and It seemed reasonable to conclude that a lower TA of 60 to 70 might be better, despite all the "warnings" to keep the TA higher. At a TA of 70 my pH will seem to stabilize around 7.8, but this is just a tad high on the saturation index all other parameters considered. I was wondering if I should just live with it, or try an even lower TA.

I am glad that others have used lower TA, my next stop will be TA in the 60's to see how that goes.

I am pretty satisfied with having a FC of 3 when I test it near sundown, which would be the lowest it gets right before re-dosing at night. I am not immune to errors and will get the occasional lowball level, sometimes I wonder if the chlorine jug is really the potency it claims to be.

 

[KJB1]

Getting your TA to 50-60ppm will slow your pH rise and lower your CSI as will keeping your pH in the low 7s if possible. Test your fill water for TA and CH to anticipate effects of adding water. Don't be in a rush to add sodium bicarbonate when your TA is above 50ppm especially if your fill water is high in TA.

That's exactly what I do in the less extreme desert. No reason to keep the TA at 70-80. With evaporation and high TA fill water my TA stays at 50-60 during the summer. In winter I add a little baking soda sometimes.

 

[Mdragger88]

Those low ta “warnings” are for those who use acidic pucks & “shock” as standard practice.
Any ta above 50 is fine if you’re using liquid chlorine or a swcg for daily chlorination.

 

[Tomk2]

That's exactly what I do in the less extreme desert. No reason to keep the TA at 70-80. With evaporation and high TA fill water my TA stays at 50-60 during the summer. In winter I add a little baking soda sometimes.

Playing with the LSI calculators, I can really get away with a lot more variation in pH and TA in the winter, when water temperatures drop into the 50's . This is my first summer trying to manipulate the LSI, I am curious what is going to happen with the first monsoon storm to it my pool.

Those low ta “warnings” are for those who use acidic pucks & “shock” as standard practice.
Any ta above 50 is fine if you’re using liquid chlorine or a swcg for daily chlorination.

That makes A LOT of sense!

 

[Mdragger88]

TA - Further Reading

www.troublefreepool.com

CSI and LSI - Further Reading

www.troublefreepool.com

 

[Tomk2]

Anyone ever see unexpected chlorine levels with different brands of liquid chlorine? I was buying Clorox at Costco, but couldn't get there last week. So I bought the 1 gallon two pack of Kemtech at the grocery store. Clorox claims 7.55%, Kemtech claims 10%. Interestingly, it seems that I need to put the same volume of Kemtech in even though it is supposed to be a higher concentration. Not that I exactly measure the chlorine, but I figured a third more percentage in the Kemtech would make a jug last longer.

 

[Mdragger88]

Clorox should not be used because it contains Cloromax which is a polymer. Best to use unadulterated liquid chlorine.
Always check the date codes - your kemtech stuff could have just been old or stored in the heat so it degraded.

Chlorine Date Code Decoder - Further Reading

www.google.com

 

[Tomk2]

Clorox should not be used because it contains Cloromax which is a polymer. Best to use unadulterated liquid chlorine.
Always check the date codes - your kemtech stuff could have just been old or stored in the heat so it degraded.

Chlorine Date Code Decoder - Further Reading

www.google.com

So it does. My Kemtech chlorine is dated May of this year. However, EVRERYTHING delivered to Phoenix this time of year has been stored in the heat somewhere, and who knows how long.

 

[Mdragger88]

Walmarts around here usually keep their liquid chlorine inside.
Got any hasa dealers around you?

Find Where You Can Buy HASA Products | HASA

Want to purchase HASA products for your pool or spa? Find out which of our partnered dealers sell HASA Sani-Clor®, Hasachlor®, Classic Bleach and Blue Whale Sanitizer.

hasa.com

 

[Tomk2]

Walmarts around here usually keep their liquid chlorine inside.
Got any hasa dealers around you?

Find Where You Can Buy HASA Products | HASA

Want to purchase HASA products for your pool or spa? Find out which of our partnered dealers sell HASA Sani-Clor®, Hasachlor®, Classic Bleach and Blue Whale Sanitizer.

hasa.com

The grocery stores keep it inside also. But they are delivered by truck, temperature this afternoon was 114 degrees. The temperature inside non-cooled vehicles gets in the 160's rather fast. Even products from refrigerated trucks get spoiled in transit, either from the compartment not being able to keep up with the heat, or how fast it warms up between the truck and being put back into refrigeration. Left on the dock for a hour? Your milk is spoiled when you open it at home. Unless chlorine is specifically transported in temperature controlled trucks, it has been subjected to high temps during delivery to the Phoenix area during the summer. And you have no way of knowing how long. It doesn't matter what store or what brand.

Breakdown of Bleach Over Time by Storage Temp - Further Reading

www.troublefreepool.com

That might explain why I needed to use about the same amount of liquid chlorine that was a higher concentration than Clorox? Since learning about the polymers in Clorox, I no longer consider it a cheaper alternative, so it is what it is.

 

[BDY]

You can control the chlorine you buy with regards to date codes and strength, as well as how you store it and for how long. You can’t control how it was transported or stored before you get it. It’s one of those things that causes variance in expected FC along with weather, bather load etc. Hence the testing frequently.

In your climate given the need to chlorinate the pool most of the year (as opposed to northern pools) I would seriously consider installing a SWG…especially if you have a variable pump. It will pay for itself many times over in cost and convenience. Get one at least 2x your pool size.

SWG How It Works - Further Reading

www.troublefreepool.com

 

[Mdragger88]

Yes! A swcg makes fresh chlorine in your back yard!

 

[Tomk2]

I just had the pool filtration replaced and upgraded 4 years ago. We did consider Saltwater. When I asked 4 colleagues who had converted, 3 regretted it, and one was ambivalent. The company who was servicing my equipment was ambivalent as well, so we didn't convert. Four years later, I continue to hear more people complain about switching than recommending it. None of the people I talk to maintain the pool themselves, so I am unclear on why they are not satisfied.

Water temperature in the 90's now. Ugh.

 

[Mdragger88]

None of the people I talk to maintain the pool themselves, so I am unclear on why they are not satisfied.

It is not set it & forget it - nothing is. You must still test & adjust all the pool’s parameters as needed the only difference is you have an apparatus that feeds your pool its daily dose of fc if you set it correctly.
People get sold on a swcg (often undersized) & told that it’s maintenance free which is untrue - most of those people end up unhappy. Undersized units & improperly managed ph & ch lead to early cell failures/short cell life which make for an expensive venture. These mismanaged things can also lead to pool problems in general.
Getting one that’s rated for at least 2x’s your pool’s volume and following
(FC/CYA Levels &

What Are My Ideal Pool Levels?

Use our tool to find ideal chemical levels for any swimming pool. Check TFP recommended levels on pH, free chlorine, cyanuric acid, and more.

www.troublefreepool.com

Make the pool care workload much simpler.