Hello--

New user here. I have been lurking for a while -- you guys are GREAT, I have learned a lot. Here's a question that I think is right up your alley and I would really appreciate some input.

We have an APEC whole house system (coconut carbon filter then water conditioner) plus RO at the kitchen sink. To be clear, by water conditioner, we are talking about a system that purports to neutralize calcium and magnesium so that they form crystals that move through the water without clumping together to form scale. (From their website: This system uses an advanced ceramic media that effectively attracts and neutralizes hard water properties without the need for regeneration, backwashing, or electricity. When water comes into contact with the catalytic surface of the media, hard water agents calcium (CaCO3) and magnesium become attached to the ceramic granules and are instantly converted into a scale resistant crystalline form. These crystals are harmless, neutral, heat resistant, and completely stable and will not attach to any surfaces like your pipes and heaters to cause lime deposits. When the crystals reach a size in the range of nano-meters (one billionth the size of a meter) they detach and are carried away by the water flow. These nano-crystals are relatively insoluble, effectively isolating hardness up to 25 grains/gal. (420 mg/L) from the water chemistry.). This was sort of a leap of faith for us but we definitely did not want a salt-based system.

We originally got this thinking we would use RO water in the machine, which we now know is wrong. Eventually, we decided to use the RO water and add back minerals. I don't make solutions, I just use a gram scale to add .8 gr epsom salt and .15 gr baking soda per gallon of water. Usually results in about 115 TDS.

Now I am questioning if I can just use the water from the tap rather than the RO. That water goes through the carbon filter and the conditioner so, theoretically, it should be free of chlorine and other unwanted compounds that could affect taste and aroma and it should pass through the machine without causing scale or maybe with a reduced propensity to form scale. FYI, the water from the tap is showing TDS around 205, so within SCAA limits. I have not done further testing (hardness, alkalinity, pH) yet.

A few questions:
1. Conditioner system aside, how much of a risk is scale build up at around 200 TDS? Does the SCAA recommendation suggest I shouldn't worry about that to begin with?
2. Anyone have any experience with this type of water conditioner system? Does it work? At water with a TDS around 200, to what extent would it be successful in preventing or slowing the rate of scale formation? Would you trust putting conditioned water through your machine?
3. How can you examine the machine to see if you are building scale rather than just waiting for problems to start ? I can take the cover off but I have no idea where to look to see if it is building scale.

Thanks in advance!

If you are talking about a cation exchange resin water softening filtration system, such a system exchanges sodium for calcium and magnesium cations and does not form calcium and magnesium "crystals" that circulate harmlessly (i.e. without forming scale) in your home plumbing and appliances. Replacing sulphate anions with say chloride in "permanently hard" salts like magnesium sulphate can make them "temporarily hard" but that would be of little practical benefit for your intended goal of reducing scale in espresso machines.

Can you supply a reference to the house water conditioner you are talking about?

I'm pretty sure that the APEC water conditioner is not a cation exchange softener. It is a TAC or NAC (template assisted nucleation) conditioner that uses a ceramic coated polymer to create crystals that stay suspended and don't form scale. TAC has been demonstrated to work in water heaters, but I'm unsure if that translates to effective scale prevention in espresso boilers. I have noticed that one reputable company, Optipure, uses it in their ScaleX2 system for use in coffee brewers.

We had some discussion related to TAC systems here on HB a while back: Template Assisted Crystallization (TAC) Water conditioning

curiousone wrote:1. Conditioner system aside, how much of a risk is scale build up at around 200 TDS? Does the SCAA recommendation suggest I shouldn't worry about that to begin with?

200 ppm TDS could certainly be very scale prone if much of that were due to calcium and carbonate. To do a good guess you need to know the hardness and alklalinity of the water and do an LSI calculation per Jim Schulman's Insanely Long Water FAQ.

curiousone wrote:2. Anyone have any experience with this type of water conditioner system? Does it work? At water with a TDS around 200, to what extent would it be successful in preventing or slowing the rate of scale formation? Would you trust putting conditioned water through your machine?

Perhaps others can weigh in about that. Given that there are ion exchange treatments that have been around a long time that are straight forward and known to be effective, I think I'd be reluctant to rely on TAC. If I had calcium hardness and alkalinity numbers that indicated light if any scale potential, then I might give it a try.

curiousone wrote:3. How can you examine the machine to see if you are building scale rather than just waiting for problems to start ? I can take the cover off but I have no idea where to look to see if it is building scale.

That is the rub. With a conventional softener you can use simple drop titration kits to measure the hardness and the alkalinity of the untreated and treated water and do an LSI calculation to see about how much it might scale. But those measurements don't tell you much with TAC -- the hardness and the alkalinity of the CaCO3 crystals do show up in the measurements, so treated and untreated water looks about the same.

To keep an eye out for scale in the steam boiler you can look at the water conductivity probe, or remove a fitting like the anti-vac valve and peek in there or use a boroscope. To check for scale in an HX or DB E-61 you can easily remove the mushroom and look for scale there: Checking an E61 Espresso Machine for Scale

I should add that if you are measuring your TAC treated water with a TDS conductivity meter, the mineral content (dissolved and suspended) in the water is likely higher than what your meter indicates. I've been told (and it makes sense chemically) that if you do GH (EDTA chelation) and KH (acid titration) tests, the numbers reflect the hardness and alkalinity of the suspended crystals as well as the dissolved mineral.

Here is the main non-commercial (and so far the only one I've found) study of the scale inhibiting effectiveness of TAC water softening technology:

https://www.waterboards.ca.gov/water_is ... teners.pdf

It was interesting to read and at least when TAC was used within the experimental protocols of the study it seems to have prevented scale build up compared to no treatment at all. Note that according to this study even "magnetic" water softeners seemed to have some benefit (about 50% reduction compared to no treatment). TAC was deemed to provide about 88% reduction (though cation exchange resins provided more...about 99% reduction).

Read the protocols closely. The study was geared toward seeing how effective "alternative" water softening treatments would be in reducing scale formation in domestic "hot water heaters" {pet peeve...they are just "water heaters"]. So the test temperatures were at 60 and 80 degrees Celsius, which is considerably lower than the temps in espresso steam boilers, especially those maintained at higher pressures.

I understand the hypothesis by which these devices are supposed to prevent scale build up...i.e. the ceramic/bead matrix is supposed to make the scale causing salts to aggregate into larger crystals that have less tendency to "stick" to metallic surfaces and thus just pass through the plumbing.

My concern which has not been answered so far as I can tell is how well do these devices prevent scale, compared to more proven methods like cationic resin exchangers, water distillation, and RO, in espresso machines with steam and brew boilers that operate at much higher temperatures and with smaller water volume capacities and more restricted water passage orifices than are found in domestic water heaters?

My opinion, from what I've read so far, is that TAC may reduce scale to some degree, but almost certainly will not do so nearly as well as the more proven traditional methods.

In addition to the considerations Nick pointed out, I'd be concerned about how these crystals behave in a steam boiler, where distilled water is sent out the steam wand, leaving a higher and higher concentration of crystals in the boiler.

They may be quite effective at reducing scale formation in lower temperature hot water heaters (I mean, really. If the water is hot, no need to heat it) where mineral accumulation is not likely. But the study understandably has no data on what happens when this crystal-laden water is "thickened" by pulling steam off. Mass is mass, so even if the water doesn't technically form scale, these crystals will eventually precipitate out of solution when their concentration reaches the saturation limit of the water.

What happens then?

My mind goes to memories of making rock candy. So I envision stalactites forming off the water level sensor and an eventual ec5asing of the boiler floor with solid calcium and magnesium crystals.

But good news!

This encasing will not technically be scale

This is all total conjecture, but reasons why I would be hesitant to use TAC water in a steam boiler. Obviously, mineral accumulation can be managed by ensuring you have a high turn over rate in the steam boiler. I use my hot water spout daily for rinsing baskets even though my water is not prone to scale. I do this because my water has the potential to scale if the concentration increases, and if you don't get the high-concentration water out of the boiler regularly, that's exactly what will happen.

Cheers!

- Jake

Thank you for taking the time to provide this level of detail. I will get a GH/KH test when I need to order dog food from chewy, I know they carry that.

I am assuming from the responses that it is probably just safer to continue to do what I am doing and use the RO water re-mineralized with epsom and baking soda.

Depending on what the hardness tests show (which I will share when I get it), what about using a percentage of tap water to re-mineralize the RO instead of adding epsom and soda. I wonder if we could calculate a percentage that would get us in the right range.

I have a Profitec 600 so I am assuming I can take the mushroom off to check there for scale.

I just drained and re-filled the steam boiler the other day with the re-mineralized RO water. So assuming I used the tap water, do we think that draining the boiler periodically would remove whatever accumulates there, whether in crystal form or as scale?

Thank you for locating this study, I had not found that. Very interesting. One thing I noticed is that the waters they used in the testing all had TDS at least double what mine is (obviously, I don't know the hardness so we can't compare that) so I would assume the effectiveness of the system in preventing scale would be higher than 88% at lower TDS and hardness levels.

Still, I think you are right about the higher temps, pressure, and smaller orifices involved in an espresso machine vs a water heather.

Extremely helpful, thank you!

One final thought/question on this: I plugged some hypothetical numbers in the La Marzocco water calculator. I wanted to see what they say about 200 ppm TDS if everything else is normal and it says there is a low scaling potential. However, I noticed that if you adjust the pH slightly upward to 7.5 it says it will cause scale. I had not seen the interplay of pH and hardness discussed anywhere in my research on this issue. Any thoughts on that?