How to measure filtered water?

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
esbndk

#1: Post by esbndk »

I have an inline BWT BestMax Premium for my Bianca.

I would like to test the water from the filter, mostly PH, can i use strips or drops?

I know I cannot test GH in any meaningful way, what about KH

There is a cafe in my building and I got a look at his water analysis.

GH 27
KH13
PH 7.6
Salt 0,013
Dh-CDH 14

Then did my own test:
GH 18
KH 11

Now I know that the water in my city gets blended from different water plants, but it just seems weird to me that we are off by 11 on total hardness

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homeburrero
Team HB

#2: Post by homeburrero »

esbndk wrote:I would like to test the water from the filter, mostly PH, can i use strips or drops?
I know I cannot test GH in any meaningful way, what about KH
Test strips can be used to measure pH, GH (total hardness) or KH (alkalinity) but they are not very precise or reliable. Measuring pH can be troublesome as it may depend a lot on the amount of dissolved CO2 in the water, so for coffee water purposes you may be better off just looking at your alkalinity, which is measured by a KH drop kit or test strip.

Drop titration kits are much better than test strips, but most of them are still not very precise. The popular kits, like the API fishcare GH & KH kit, use a small 5 ml sample, and can barely distinguish a sample with 18 mg/L from one with 36 mg/L of CaCO3 equivalent hardness or alkalinity. You can use a larger sample to get a little better precision - - using a 10 ml sample will give you around 9 mg/L at one drop, 18 mg/L at two drops, 27 mg/L at 3 drops, etc. That's perhaps good enough for you to determine whether your KH and GH numbers are acceptable for espresso machine water.


esbndk wrote:Then did my own test:
GH 18
KH 11
You don't say how you performed that test. For a home kit test I think it's within good agreement with a water that has been laboratory analyzed at GH 27 mg/L and KH 13 mg/L.
Pat
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esbndk (original poster)

#3: Post by esbndk (original poster) »

I used a drop test (NTLabs 5ml) to test my mains water.

My numbers were German Degrees (DH)

But what I was most unsure of is how to test the water that has already been through the filter.

I seem to recall reading that these test kits do not work on filtered water.

I found a PH test strip kit that specified it could not be used on water that had been through an ion exchange filter.

Could I use any PH drop test kit?

And thanks for the rest of the answers, I always thought these drop tests had to be imprecise, the drops have to be different.

I live in an apartment complex so I don't really know what is done to the water I get

I want to make sure my water from the filter is not too low in PH

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homeburrero
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#4: Post by homeburrero »

esbndk wrote:My numbers were German Degrees (DH)
Wow. That's really getting up there!
esbndk wrote:But what I was most unsure of is how to test the water that has already been through the filter.
You can measure it with drop titration test kits. With a conventional cation exchange softener you expect a drastic change in GH and no change in KH. If you measure it before and after with a conductivity 'TDS' meter you would see no change, maybe even a slight increase after softening.

With a decarbonizing filter (aka WAC resin filter, aka hydrogen ion exchange filter) you would see a drop in both GH and KH. You also expect a drop in pH and in TDS.

With some treatment systems, like template assisted crystallization (TAC) you would not see a reduction in GH nor KH. In theory the GH is not as scale forming, but it would still be measured by the kit.
Pat
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homeburrero
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#5: Post by homeburrero »

esbndk wrote:I found a PH test strip kit that specified it could not be used on water that had been through an ion exchange filter.
Could I use any PH drop test kit?
pH is tricky. Right after a WAC filter it may come out alarmingly acidic but then after it loses dissolved CO2 it would come back up. A titrateable acidity drop titration kit should work, or an inexpensive calibrated pH meter. Not sure you need that though.
esbndk wrote:I want to make sure my water from the filter is not too low in PH
For evaluating water and doing LSI calculations it's often best to just go by the alkalinity measurement. See Jim Schulman's Insanely Long Water FAQ about doing LSI calculations.

P.S.
You may see fairly big differences over time and at different locales in those numbers, especially where a water utility has more than one source and plant. It may switch between plants when one shuts down for maintenance or when one or the other experiences a scarce supply.
Pat
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esbndk (original poster)

#6: Post by esbndk (original poster) »

homeburrero wrote:With a conventional cation exchange softener you expect a drastic change in GH and no change in KH.
I have a BWT BestMax Premium it contains an activated carbon filter and various other mechanical filters and what they describe as:

"High performance ion exchanger
BWT Magnesium Technology
Magnesium add-on in
exchange to calcium"

As I have understood it, it increases GH (Total/Genral Hardness) and decreases KH (K for Karbonat Carbonate Hardness) which is what we want to decrease scaling. This (as I understood it) is beacause it switches out the scaling minerals for non/lesser scaling minerals and it adds Magnesium.

Am I wrong?

I guess mine is a TAC filter after reading up on it for a few minutes.

But if you could dumb it down a bit for me :D

I will try and make a GH/KH drop test on my filtered water and see what it says

esbndk (original poster)

#7: Post by esbndk (original poster) »

OK - I give up.... I don't have the required knowledge nor equipment to do anything productive here.

I measured the KH from the filter with a BWT test kit, which is old so maybe that was the problem, came out as 12 DH (10ml sample 1 drop=1DH)

When measured with the NTLabs new kit it was 7 (Kit is 5ml sample 1 drop=1DH - I used 10ml sample 2 drop=1DH)

But the reply suggesting it, said 1 drop = 9mg/L and I don't have the knowledge to determine if I just wasted time and reagents.
They are different colors as well, so maybe they have different requirements...

So I will just have faith that I at least know the raw water values as they were pretty consistently around 18-20. And trust that my filter is doing what it is supposed to.

Chemistry is hard....

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homeburrero
Team HB

#8: Post by homeburrero »

esbndk wrote:I have a BWT BestMax Premium it contains an activated carbon filter and various other mechanical filters and what they describe as:

"High performance ion exchanger
BWT Magnesium Technology
Magnesium add-on in
exchange to calcium"

As I have understood it, it increases GH (Total/Genral Hardness) and decreases KH (K for Karbonat Carbonate Hardness) which is what we want to decrease scaling. This (as I understood it) is beacause it switches out the scaling minerals for non/lesser scaling minerals and it adds Magnesium.

Am I wrong?

I guess mine is a TAC filter after reading up on it for a few minutes.
Not a TAC (template assisted crystalization) filter. Both the Bestmax and the Bestmax Premium use WAC (weak acid cation) softening resins, which are often referred to as decarbonizing filters in newer coffee water technical discussions*.

The Betsmax filters, like all decarbonizers, reduce KH as well as GH, and acidify the water a little. These three factors all work to reduce limescale deposition. Note that these filters have you set the bypass and estimate the filter replacement volume based on the KH measurement of your water. The Bestmax Premium differs a little in that some of the resin exchanges calcium ion for magnesium ion. This particular action doesn't reduce the GH nor the KH, but by shifting some hardness from calcium to magnesium, it would also tend to reduce limescale. Some think that it might improve taste but that's iffy.


esbndk wrote:I measured the KH from the filter with a BWT test kit, which is old so maybe that was the problem, came out as 12 DH (10ml sample 1 drop=1DH)
These kits should have an expiration date, and if they are open and they evaporate that will also make them less accurate.

esbndk wrote:When measured with the NTLabs new kit it was 7 (Kit is 5ml sample 1 drop=1DH - I used 10ml sample 2 drop=1DH)
I think You did that correctly - - with a 10 ml sample, 14 drops would be 7 °dKH. German degrees (°dH) are a perfectly good unit of chemical equivalence, and are used by BWT. You can easily convert them to any other unit of chemical equivalence like French degrees (used in Italy also), or ppm CaCO3, which is fairly standard here and in most coffee water discussions. when reporting these measures you do always want to specify your units. 1 German degree is equal to 17.85 ppm CaCO3 equivalent. This is true irrespective of whether you are measuring KH, GH, calcium hardness, magnesium hardness, etc. When a hardness or alkalinity measure just says ppm or mg/L, you can generally assume that it's a measure of CaCO3 equivalent. Often you see "ppm CaCO3" or "mg/L as CaCO3", which mean the same thing.


esbndk wrote:So I will just have faith that I at least know the raw water values as they were pretty consistently around 18-20. And trust that my filter is doing what it is supposed to.
You do want to use that raw water °dKH to set your bypass, and to decide when to replace your filter based on the tables in the BWT instruction sheet.

* Some discussion of conventional vs decarbonizing softeners can be found here: Water filter cartridge advice sodium vs. hydrogen ion exchange The SCA Water Quality Handbook is excellent source of info including the basic chemistry you need. Chapter 16 of The Craft and Science of Coffee also covers much of the same info.
Pat
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esbndk (original poster)

#9: Post by esbndk (original poster) »

You say I should set the bypass according to KH not GH?

Is GH not Total Hardness?

BWT manual says Total Harness in d°

So I have mine on 1 as my GH is 18 in d°

I just read the BestMax non premium and they go by d°KH, So I am guessing mine is set correctly.

Would you say I am just wasting my money by going with the Mg adding filter? Would BestProtect give just as good taste?

BestMAx and BeastMax premium cost the same here, I use the S version (340L per year)

And thanks for explaining this : )

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homeburrero
Team HB

#10: Post by homeburrero »

esbndk wrote:You say I should set the bypass according to KH not GH?
Is GH not Total Hardness?
BWT manual says Total Harness in d°
You are correct, the instruction manuals for the Bestmax Premium tell you to use total hardness (GH) to set the bypass and estimate the lifetime, and the regular Bestmax instructions advise you to use the "carbonate hardness in °d" (°dKH) measure, which in this case is a measure of alkalinity. (For most natural water, carbonate hardness is equal to alkalinity, and all the simple test kits for KH, carbonate hardness, and temporary hardness are measurements of alkalinity - - acid buffering capacity).

I'm not sure what BWT's rationale is for the different measures for the Bestmax Premium vs the Bestmax, but it shoudn't matter much. Using total hardness (GH) should tend to give you a lower volume capacity and in that sense is more prudent.


esbndk wrote:Would you say I am just wasting my money by going with the Mg adding filter? Would BestProtect give just as good taste?
I'm not a beleiver that increasing the Mg improves the taste, but there are those who think that it does for some coffees. Replacing some Ca with Mg certainly would tend to make the water less scale prone.

The advantage of the Bestprotect, which uses a conventional softening resin and is always used at zero bypass, is that it reliably reduces the hardness to very low levels without reducing the alkalinity and without acidifying the water. Some recommendations, including the SCA Water Quality Handbook caution that treating very hard (over 17 °dH) water with an inline decarbonizing softener may over acidify the water*. If you used a Bestprotect it would avoid that issue, but I'm not sure that it would improve the taste, because with that filter your water would be coming out with a higher alkalinity than is usually recommended for taste.

* SCA Water Quality Handbook , section 9.2:
"The working principle of the decarbonizer that reduces total hardness and alkalinity is based on the exchange of magnesium or calcium ions by protons. This means that although the hydrogen carbonate is protonated and therefore not an acid buffer anymore, it is still present in the form of carbonic acid, which in turn is in a constant exchange with dissolved carbon dioxide. If the treatment is done by an in-line system where the carbonic acid cannot escape as carbon dioxide, it leads to two effects. Firstly, the pH of the treated water will decrease and in case of a water with a high starting level of total hardness (i.e. > 300 ppm CaCO3), this can effectively make the treated water so acidic that the risk of corrosion increases significantly. Secondly, a large amount of carbonic acid will also lead to excessive crema production during the extraction of espresso."
Pat
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