Bicarb Startup With Extremely Soft Water

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J

JFarr

Active member
Mar 20, 2023
43
Austin texas
I'm preparing to have new plaster installed so I have been researching it.

I tested my water at the hose and it's:
PH: 9.65
TA: 70
CH: 40

My understanding is that this water would be extremely aggressive towards new paster. So I want to use the bicarb startup method advocated here.

However all of the examples I've seen assume combined TA and CH of the fill water start off around 200 to 250ppm. Mine is only 110ppm combined.

So I'm wondering if my fill water is just too far out of spec for the bicarb method to be utilized. If that's the case I'm guessing my only other option would be to have pretreated water trucked in.

Thank you for your time,
Joseph
 
9.65 pH is excessively high for any kind of of water. Is this a well or city water??

Are you sure you got the measurements right?
 
Is that straight from an outdoor spigot or at the main line that runs into your home? There’s no water conditioner (alkaline filter) being used in your home, correct?
 
JoyfulNoise said:
Is that straight from an outdoor spigot or at the main line that runs into your home? There’s no water conditioner (alkaline filter) being used in your home, correct?
Click to expand...

It's from an outdoor spigot nearest my pool. The one I would use to fill. My kitchen sink tests the same. There is no filter or conditioner that I know of. We've only owned the house about 10 months though.
 
JFarr said:
I tested my water at the hose and it's:
PH: 9.65
TA: 70
CH: 40
Click to expand...
That pH seems unlikely.

Did you calibrate the meter?

Did you check it against a solution like distilled water?

In any case, even if it is that high, the bicarb will lower the pH to about 8.3 and you can use acid, if necessary, to lower the pH.

You can also add some calcium if the plaster manufacturer recommends it but not on the same day as adding baking soda.
 
Based on the instructions, you can add 290 ppm of bicarb to get the TA to 360 and then the combined would be 400 ppm.

Or, you can add some calcium first and then add enough bicarb to get to a combined of 400 ppm.

Do not add bicarb and calcium on the same day.

In my opinion, this is a pretty high CSI and it might risk scaling.

In my opinion, a more balanced CSI of about 0.0 is a better choice.

The Bicarb Start-up and Why it Works

The following information on Bicarb start-ups is applicable to all newly plastered swimming pools, including color, quartz, and pebble aggregate finishes. The first step for a superior start-up is to wait at least six hours (after the plastering is completed) before turning on the water to fill...
www.troublefreepool.com www.troublefreepool.com

A Bicarb Start-up guide for TFP members

It is an unfortunate fact that most tap water used to fill swimming pools is often soft, aggressive, and somewhat harmful to a new plaster surface. Therefore, in order to not damage a new plaster surface, the tap water needs to be “balanced” (meaning for new plaster, the CSI should be at least...
www.troublefreepool.com www.troublefreepool.com

"Step 2 – Calculating the Chemical Dose for adding sodium bicarbonate (Bicarb)

Add the Alkalinity and the Hardness numbers together.

Then we subtract that number from 500.

The result is the amount of sodium bicarbonate in ppm to add.

For example, if the fill water Alkalinity is 90 and the fill water CH is 200, then 210 ppm of new bicarbonate needs to be added: 500 – (90 + 200) = 210

Use TFP’s “Pool Calculator” to determine amount of sodium bicarbonate to add to the barrel based on gallonage of the pool.

If the combined levels of the alkalinity and the calcium hardness of the fill water is 500 ppm or higher, and the pH is between 7.2 and 8.2, then no addition of sodium bicarbonate is necessary.

Just fill with that water - it is already perfect for new plaster pools.

EDIT 8-14-2018: I have determined that the maximum combined TA and CH can be limited to a total of "400 ppm" but is also okay to go as high as 500 ppm combined total as mentioned above."


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onBalance said:
A Bicarb start-up prevents the loss of calcium hydroxide from the plaster, which preserves a dense (non-porous) surface, and no plaster dust forms. Instead, it converts calcium hydroxide WITHIN the plaster surface into calcium carbonate, creating a harder, denser, smoother, and more durable surface. And there is no increase of calcium hardness in the pool water.
Click to expand...
Calcium hydroxide is more soluble than calcium carbonate, so calcium hydroxide will dissolve from the plaster even with a balanced or high CSI.

However, if you have a high level of carbonate, the carbonate is more likely to replace the hydroxide as it is lost.

At a pH of 8.3, 99% is in the form of bicarbonate and 1% is carbonate.

At a pH of 9.65, about 81.7% is bicarbonate and about 18.3% is carbonate.

100Ca(OH)2 + 100HCO3- --> 100CaCO3 + + 100H2O + 100OH-


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y = 100-(100/(1+10^(10.3– x))) and y = (100/(1+10^(10.3– x))) , x from 8 to 12 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.
www.wolframalpha.com www.wolframalpha.com

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JFarr said:
It's from an outdoor spigot nearest my pool. The one I would use to fill. My kitchen sink tests the same. There is no filter or conditioner that I know of. We've only owned the house about 10 months though.
Click to expand...

9.65 is way above the EPA limit for drinking water. The EPA sets the standard water supply pH between 6.5-8.5. Suppliers are allowed to deviate from that standard for SHORT periods of time if system maintenance or some other issue arises. But if that’s how your water is constantly supplied, then there’s an issue and the municipal supplier needs to be notified so they can fix the problem. It’s actually not healthy to drink highly alkaline water like that, despite what all the fitness-nuts say.
 
Ok, you guys have convinced me there is most likely an error in my testing. I'll get some distilled water and check/recalibrate my meter.

I also wonder if I mix my water 50/50 with distilled water and do a phenol red test is that a valid method for checking high ph? Or is that just nonsense?

Is there any other method for checking if my PH is really as high as the meter claims?

Thank you so much for your help,
Joseph
 

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The meter should be calibrated using the calibration standards provided. You can try checking distilled water but it has such low ionic strength that the meter may bounce around or not settle down (there are special pH probes for low ionic strength pH testing). Simple bottled water, like Dasani, should be fine to test. It’ll be somewhere between 7.0 and 8.4, typically.
 
In certain areas of the country, tap water can have a high pH above 8.5. In places of northern California, the pH is raised to 9.3 with NaOH (sodium hydroxide) to balance the very low calcium and alkalinity levels (30 ppm TA - 25 ppm CH) coming from the High Sierras. For the Austin City water, you can contact them and ask about the pH level (including the CH and TA) of their water. Given your tested TA and CH levels, a pH of 8.6 would be balanced. What is interesting, is that when your tap water enters the pool as is, the pH may raise even higher if not pre-treated.

For your tap water, a Bicarb startup can work very well. You will also need to acid some acid while the pool is filling to help the process by helping to keep the pH below 8.3. You might consider switching halfway through the filling, and change to adding calcium chloride to raise the CH while the pool fills the rest of the way. The main point being that the combined TA and CH needs to total above 400 ppm with the pH being below 8.3 and above 7.4 and the CSI (or LSI) is about +0.5. That is important.
 
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I contacted the city water to inquire about the PH and they directed me to their quarterly quality report here:

Water Quality Summaries | AustinTexas.gov

Monthly and quarterly summaries of water quality parameters in finished drinking water for major industrial users.
www.austintexas.gov www.austintexas.gov

They report the PH of water leaving our three treatment facilities at 9.7, 9.7, and 9.6 respectively. So it seems my meter is bang on.

They also report Total Alkalinity at 58, 58, and 79. So I think my test result of 70 is believable there too.

However, on hardness they report Total Hardness at 94, 96, and 107. More than double my tested value of 40. I've run the test two more times and have no discernable change in color after the 4th drop.

Is Total Hardness not the same as Calcium Hardness? Or is my testing here bad? Should I substitute their value of 100 for my 40?
 
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First let me thank everyone here for their help. @JoyfulNoise @JamesW @onBalance Thank you.

Pool builder came by today to talk about preparations as we are a week and a half from planned start of the chip out.

I tried to explain how I wanted the startup handled and why. Also, that I did not want an acid wash and why.

He basically told me that everything on the Internet is wrong and that I didn't know what I was talking about. He brought out his Leslie's test strips to prove it and informed me that I had a pH of 7.6 and CH of 250.

I told him that I didn't believe the strips were accurate and he could check with my Taylor kit if he wanted. He said he doesn't mess with the drop tests anymore because he doesn't take care of pools anymore.

I told him that I could show him the city water report and he said "the city doesn't know anything and they just do what they want." I'm not sure what that's supposed to mean.

He kept telling me that he's been doing 20 pools a year for 15 years and that I didn't know what I was talking about. Every pool he's ever done in Texas has high CH.

He also told me that a pebble finish had to be acid washed. It's required by the NPC. And it's required to get the warranty on the plaster. And that every type of finish is better if it's acid washed.

I didn't even get a chance to talk to him about measuring the water for the cement or not using accelerator.

Finally he told me that it's my pool and I can do what I want but I would have to sign a waiver and I wouldn't get any kind of warranty.

So, currently I'm very frustrated. We've already put so much time and energy into this. Luckily we haven't paid him anything yet.
 

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