Testing of Acid Neutralizer Effectiveness

[DesertEaglePt50]

Hi, thanks for reading. I have read many threads about acid neutralizers on this site. I apologize if this question was already addressed, it might just be a gap in my understanding. My interest in this topic isn't hypothetical, but it was simpler to pose the question that way.

Let's say I just moved into a house that has copper piping and an acid neutralizer. I do a complete dump and refill of the calcite-only media. I send my water out to be tested, because I want to make sure my pipes are protected. How do I know that my pipes are protected from now until I refill the media at 1/3 the tank volume? Can I determine this from one test of the treated water when the calcite is full? Can my followup testing as the calcite is depleted simply be for pH and plug that into an LSI calculator or do I need a complete water test because the other factors affecting LSI cannot be assumed to be constants?

Thank you!

 

[Reach4]

Calcite tanks sometimes have backwash to keep the media from sticking together. Others, called "upflow" don't. You could run a high volume of water thru every couple of weeks to expand the bed and keep things from cementing together. In that cemented state, channels develop, and a lot of the media does not participate in the neutralizing.

If your tank is unpainted (natural tan), you can see the calcite level by backlighting the tank in the dark. You can also see the bed expansion during a backwash.

I like the cheap pH meters that you use a screwdriver to calibrate each time. You get a packet of buffer salts, and mix that with 500 ml of distilled water. Store the solution in a jar with a lid.

Store the tip in buffer solution. You can put some solution into the cap, and store the device cap down.

 

[Sponsor]

 

[Valveman]

Moving to water softener forum.

 

[DesertEaglePt50]

Calcite tanks sometimes have backwash to keep the media from sticking together. Others, called "upflow" don't. You could run a high volume of water thru every couple of weeks to expand the bed and keep things from cementing together. In that cemented state, channels develop, and a lot of the media does not participate in the neutralizing.

If your tank is unpainted (natural tan), you can see the calcite level by backlighting the tank in the dark. You can also see the bed expansion during a backwash.

I like the cheap pH meters that you use a screwdriver to calibrate each time. You get a packet of buffer salts, and mix that with 500 ml of distilled water. Store the solution in a jar with a lid.

Store the tip in buffer solution. You can put some solution into the cap, and store the device cap down.

So the acid neutralizer in question does backwash. I believe the backwash effectively expands the media, because when I go to refill it, the the riser tube lifts up with the valve and I have to dump out the remaining media. The neutralizer tank is painted, unfortunately.

Even with a fresh bed of calcite, the pH falls below 7 when there is a sustained demand for water, such as when showering or doing laundry. This acid neutralizer has protected the copper pipes for decades (when maintained), but I just starting taking pH readings because it is such a chore to refill the media, and I wanted to not do it more or less often than needed. It is my mom's house, so I know the history, but I have no access to the records from when the neutralizer was professionally serviced.

The water is very hard, so on an LSI basis, the copper pipes may be fine, and the pH alone may not tell the story. This is why I want to get testing done. Assuming the LSI comes back fine, where do I go from there? Can i just monitor the pH or do I need to keep getting professional water testing done so I can monitor the LSI?

 

[Reach4]

A calcite tank should have a fill port to allow topping up calcite without removing the valve.

If you redo your system, you might consider an injection system.

Have you played with an LSI calculator? Get a Hach 5-B hardness kit. I would enter the number of grains X 17.1 as the calcium carbonate mg/l (ppm) and put zero for magnesium carbonate. I am not a pro.

What do you measure pH with? Test strips are typically not so good.

Injection systems come in two primary forms... one fixed injection rate that runs when the pump runs. That is cheaper. You must inject before the pressure tank, and the pressure tank has to deal with any precipitate.

Proportional injection needs a sensor to measure flow, and tells the pump to pump at the needed rate. That would normally inject after the pressure tank, and before the settling/contact tank (which is used if there is significant precipitate).

 

[DesertEaglePt50]

A calcite tank should have a fill port to allow topping up calcite without removing the valve.

If you redo your system, you might consider an injection system.

Have you played with an LSI calculator? Get a Hach 5-B hardness kit. I would enter the number of grains X 17.1 as the calcium carbonate mg/l (ppm) and put zero for magnesium carbonate. I am not a pro.

What do you measure pH with? Test strips are typically not so good.

Injection systems come in two primary forms... one fixed injection rate that runs when the pump runs. That is cheaper. You must inject before the pressure tank, and the pressure tank has to deal with any precipitate.

Proportional injection needs a sensor to measure flow, and tells the pump to pump at the needed rate. That would normally inject after the pressure tank, and before the settling/contact tank (which is used if there is significant precipitate).

The calcitite tank does not have a port. The house has had a calcite neutralizer for as long as I know, and there was never a problem with pipe corrosion except when the neutralizer was not serviced in 2+ years. The pH of untreated water is 6.1, so theoretically within the capability of a calcite neutralizer. The water is very hard, so I wonder if the pro set it up on an LSI basis, rather than pH alone, so as to not make the water unnecessary hard or scale-forming. Alternatively, the backwash valve could be allowing untreated water through.

I use an Aphera pH60. I always back test on a known pH when I am done taking measurements to rule out any drift on the readings. The meter stays true so I trust it.

I have looked at LSI calculators on the web. Temperature and pH I can measure. I expect that it would be cost prohibitive to do my own readings of the other three measurements. Maybe it makes more sense than sending out multiple test samples over time to a professional lab, but I haven't looked into the cost of doing my own LSI readings and calculations.

 

[Reach4]

Three other numbers are TDS. How about using a cheap TDS meter?

Ca2++ (function of hardness). I should re-think what factor to use. Hardness grains x 17.1 is probably too high, because that reported number is normalized to calcium carbonate (sum of Ca and carbonate. So I should deduct for the carbonate ion.

HCO3-- that is the carbonate ion. So maybe get a lab water test once, and presume it is not changing much. The softener will remove CA++ but not carbonate.

 

[DesertEaglePt50]

So let's say I get a tds meter. I would still need alkalinity, which is expressed as CaCO3 only, and Calcium, which is expressed as Ca2+ or CaCO3. How can they both be expressed as CaCO3 but not be the same?

If I wait a day or two to test the same water sample that is left on a counter in a glass, the pH is always higher, say 7.1 to 8.1. My theory is that the dissolved CO2 decreases at a warmer temperature and when exposed to the open air. I emailed MyTapScore.com, and they said that my pH reading would probably be more accurate then what they would record at their lab, because they would effectively be testing a different sample. I don't think that Ca2+ would change with time and temperature, but I think alkalinity would.

The water is not and has never been softened.

 

[Fitter30]

Calcium forms different alkaline compounds; calcium carbonate is one such compound. Calcium Carbonate is a chemical compound having the chemical formula CaCO3. Therefore the main difference between calcium and calcium carbonate is that calcium is a chemical element whereas calcium carbonate is a chemical compound.

The Impact of TDS & pH on Quality of Drinking Water

pH in Drinking-water:

medium.com

 

[DesertEaglePt50]

To supplement the knowledge shared by members here, I looked into alkalinity testing. Essentially the test is adding an acid of known concentration drop-wise to a volume of water until the pH reaches 4.3. At this pH, all the carbonate and bicarbonate has been converted into carbonic acid. The number of drops is multiplied by a factor to give alkalinity as CaCO3.

I still don't know why the alkalinity is expressed as CaCO3 when the calcium has nothing to do with it. I don't think the acid cares whether the counter ion to the carbonate is Ca, Mg, or Na. I suppose it has to do with the LSI being focused on calcium carbonate precipitation.

I still don't know what to make of the calcium hardness portion of the LSI. Am I testing just for Ca hardness or total hardness? Does that determine whether I use units of Ca or CaC03, respectively?

 

[Fitter30]

This forum might find your answers

Water treatment & distribution Forum - Eng-Tips

Professional forum and technical support for engineers for Water treatment & distribution. Includes problem solving collaboration tools.

www.eng-tips.com

 

[Reach4]

So let's say I get a tds meter. I would still need alkalinity, which is expressed as CaCO3 only, and Calcium, which is expressed as Ca2+ or CaCO3. How can they both be expressed as CaCO3 but not be the same?

So regarding your question about why CaCO3, I expect then numbers are normalized, as they are usually for hardness. So the hardness is typically expressed as equivalent mg/l or grains of CaCO3, even tho a substantial portion of the hardness is from MgCO3. I suspect that it was easy to produce a calibration solution from a single solid compound plus water. Since Mg ions are heavier than Ca ions, if you could actually weigh the ions, total mg/l would be bigger for combined hardness than the number they cite.
https://www.lenntech.com/calculators/langelier/index/langelier.htm does not ask for alkalinity directly.

 

[DesertEaglePt50]

So regarding your question about why CaCO3, I expect then numbers are normalized, as they are usually for hardness. So the hardness is typically expressed as equivalent mg/l or grains of CaCO3, even tho a substantial portion of the hardness is from MgCO3. I suspect that it was easy to produce a calibration solution from a single solid compound plus water. Since Mg ions are heavier than Ca ions, if you could actually weigh the ions, total mg/l would be bigger for combined hardness than the number they cite.
https://www.lenntech.com/calculators/langelier/index/langelier.htm does not ask for alkalinity directly.

I want to make sure I understand what you are saying.

The difference between hardness being inputted into the LSI as Ca 2+ and CaCO3 is just a variation in the molecular weight, the mg/l difference being attributed solely to the weight of the CO3. Is that correct?
As far as Mg hardness is concerned, one Mg ion doesn't effect water hardness any more or less than one ion of Ca, the difference in the mg/l again being solely attributable to the difference in molecular weight. Is that right?

And taken together, if I took a measurement of hardness to input into the LSI, it should measure the quantity of both Mg and Ca, but express the mg/l as if Mg weighed the same as Ca. Is that right?

 

[Reach4]

That is my understanding.