Here are the latest measurements (ppm):
RO water: GH 35.8 (2 drops); KH 35.8 (2 drops); total TDS 46 (meter)
Coffee minerals: GH 89.5 (5 drops); KH 53.7 (3 drops); total TDS 98 (meter)
Tap water: total 199 (meter)
Question: could it be right that the total measured-by-meter TDS of the samples is greater than the total minerals in the samples measured by drops?
mathof2 Question: could it be right that the total measured-by-meter TDS of the samples is greater than the total minerals in the samples measured by drops?
TDS (ppm of everything in the water, as ion) and GH (calcium and magnesium only, multiplied by known factors)/KH measurements (ppm as CaCO3) are not in common units, forget the TDS.
mathof2 I haven’t and you don’t need to either 😀
Just stick to the meaningful units.
GH & KH relate to scaling potential and alkalinity (KH) in the water, KH also affects perceived acidity in the coffee produced (more alkalinity/KH = less acidity).
TDS is anything in the water, organic & inorganic, much of which has little to no effect on what we are interested in.
Course completed. Look at it as ingredients rather than ‘science’.
mathof2 Ok what I’m trying to understand here is what the RO water is. 35.8mg/l GH/KH seems high.
So as has been touched upon above a 20ml sample will give better accuracy. With a 5ml sample, when the colour changes with two drops you know the GH/KH is somewhere over 17.9mg/l and below 35.8mg/l (range between drops is 17.9mg/l). With a 20ml sample the range between drops will be 4.475mg/l….so the test is much more accurate with a larger sample.
Right now your RO is 17.9-35.8mg/l GH/KH and your remineralised water is 71.6-89.5 GH and between 35.8-53.7 KH….so the infusion adding 10.8 KH might be right. Weird formulation adding only 10mg/l alkalinity to supposedly highly pure RO water.
Now I understand what is meant by a 20ml sample (each drop to be multiplied by 4.475O). I’ll use that method tomorrow and post the results.
I have a worry that the RO water is being contaminated by a leak from the remineralisation bottle. The TDS readings on the RO water went up when I first added a remineralisation bottle to the machine, and have stayed up. I know Skuma has identified such leakage as a possible problem. But given that such leakage would be only of wanted minerals, I don’t know if it matters.
The boiler peaks a 1.4 bar, which according to a superheated steam calculator on the internet is 126.254C.
By the way, the taste of espresso made with the Skuma coffee water is delicious. It’s at least as good as the Volvic I used previously, perhaps better as it seems somehow more transparent in revealing the flavours of the beans.
mathof2 ok no need to descale the HX, flushing of the boiler regularly is going to be necessary to prevent scale build up or just schedule descaling. IIRC volvic has about twice the alkalinity of the water you are now brewing with so will mute the acidity much less which goes some way to explaining the difference in results.
I guess I’d rather flush the boiler regularly than bother with descaling.
It’s a relief to know that I can just go ahead with the system I now have.
Buon caffè a tutti!
