Magnesium level in Severn Trent water

[Eric]

Yes I had the terrible Salifert kit.

It was the acid in the kit that was the problem, not the blue indicator reagent.

Thanks James, but it does appear not to be so in this case.

What's got me now is, if alkalinity is less than ST claim, how can that be without the other ions being lower without adding acid, which I doubt they ever would. I'm always a bit suspicious of British waters reported to have either more, or equal quantities of sodium as chloride.

cc986, you have proof positive that the alkalinity of your water is less than ST claim and at most, if it doesn't turn blue in the next few days, is 89ppm bicarbonate.

[cc986]

Thank you so much Eric - I have learnt so much about water chemistry through your help!

The whole thing has made me realise that ST are providing very questionable data in their online water reports. To make matters even more confusing for the poor homebrewer, their water quality team is providing data that is different to what is being published online and they provide different data for the same time period each time they are asked.

[clarets7]

The whole thing has made me realise that ST are providing very questionable data in their online water reports. To make matters even more confusing for the poor homebrewer, their water quality team is providing data that is different to what is being published online and they provide different data for the same time period each time they are asked.

I doubt very much that the figures they are quoting are wrong, they do say the supply is from a blend of sources and the samples are taken at random, so they are probably never going to make a balanced water profile: -
"For most analysis, results are from samples taken at random in the water quality zone of your area. In some cases, results are from samples taken from water treatment supply points feeding the zone."
Maybe ask them for just the results from the water treatment supply points? At least then you may have some idea of the extremes, and use the alkalinity and TDS readings to make a best guess? But if it's always blended then maybe that's not much help

[cc986]

The whole thing has made me realise that ST are providing very questionable data in their online water reports. To make matters even more confusing for the poor homebrewer, their water quality team is providing data that is different to what is being published online and they provide different data for the same time period each time they are asked.

I doubt very much that the figures they are quoting are wrong, they do say the supply is from a blend of sources and the samples are taken at random, so they are probably never going to make a balanced water profile: -
"For most analysis, results are from samples taken at random in the water quality zone of your area. In some cases, results are from samples taken from water treatment supply points feeding the zone."
Maybe ask them for just the results from the water treatment supply points? At least then you may have some idea of the extremes, and use the alkalinity and TDS readings to make a best guess? But if it's always blended then maybe that's not much help

The last one they gave me was from the nearest water treatment site. They wouldn't give the address, but that's what they said on the phone anyway.

[Eric]

The whole thing has made me realise that ST are providing very questionable data in their online water reports. To make matters even more confusing for the poor homebrewer, their water quality team is providing data that is different to what is being published online and they provide different data for the same time period each time they are asked.

I doubt very much that the figures they are quoting are wrong, they do say the supply is from a blend of sources and the samples are taken at random, so they are probably never going to make a balanced water profile: -
"For most analysis, results are from samples taken at random in the water quality zone of your area. In some cases, results are from samples taken from water treatment supply points feeding the zone."
Maybe ask them for just the results from the water treatment supply points? At least then you may have some idea of the extremes, and use the alkalinity and TDS readings to make a best guess? But if it's always blended then maybe that's not much help

The last one they gave me was from the nearest water treatment site. They wouldn't give the address, but that's what they said on the phone anyway.

Where might you go from here?

We know that your current water supply is different from 12 months since. PeeBee gave reason why ST water might vary.
We know you currently can't depend upon ST's figures, whether that will always be so, we don't know.
We know with your Salifert kit, you can measure alkalinity sufficiently accurate for your brewing needs.
We know your TDS meter detect variations in the mineral levels of your supply.
We know ST are capable of producing some spurious mineral levels that demand reexamination, but ST don't.
We know you use Brewfather software, which I know nothing about, but nevertheless am suspicious that some of your concerns might be manifested by the water adjustment calculator in that application. I fear many such applications are written by persons more competent in programing than brewing.
The subject of your original post, "magnesium content" shouldn't be a cause of concern, only worry about it if your water has none, an essential for yeast and health ferrmentation.

This is my water, there is a minor error in the table.

S219-21.jpg (72.23 KiB) Viewed 7463 times

So for fun, using my recalibrated TDS with associated spreadsheet found today's mineral profile of my water. Then, using a TDS meter factory calibrated for NaCl solutions like yours, diluted a sample of my water with deionised water until it read 158. Then taking a reading with my home calibrated TDS meter and feeding that into my spreadsheet got the following.

Ca 35mg/l, Mg 11.9, Na 12.1, SO4 65.8, Chloride 16.6 and bicarbonate 97.6mg/l.

This one was based on readings taken between 1st Feb - 16th Feb:
Calcium 51 Mg Ca/L
Chloride 32.1 Mg CI/L
Magnesium 9.21 Mg Mg/L
Bicarbonate (HC03) 157.84 mg/L
Sodium 37.5 Mg Na/L
Sulphate 57.7 Mg/L

If you were to consider my water is utterly different to your own, but should you reduce those figures above from ST in direct relationship to the alkalinity you measured and the same given by ST, would the difference from my water adjusted by make a different beer?

Not in my book!

[cc986]

Thanks for taking the time to do that Eric. I do get what you are saying about BrewFather and had already decided that I would start using one of the others like Graham Wheeler's or Bru'n water.
P.S. My alkalinity test stayed pink!

[Eric]

Good luck.

Water supplies under pressure can absorb significant volumes of gas that take several hours to escape. In the case of CO2, the sample can become acidic and turn the indicator pink before the full requirement of acid is added. I wouldn't have expected your sample to do that as from your Salifert test, the alkalinity was measured as being much lower, but it was worth checking.

[f00b4r]

Thanks for taking the time to do that Eric. I do get what you are saying about BrewFather and had already decided that I would start using one of the others like Graham Wheeler's or Bru'n water.
P.S. My alkalinity test stayed pink!

Just be aware that different tools take different approaches to water treatment, often a cause of confusion!
Graham's calculator on here (amongst others) takes the historical approach of reducing alkalinity to the right amount for your grist and adjusting salts for changing the balance of the beer. The approach that has come out of the American homebrewing community, whose tap water can be problematic to brew with, takes a different approach (acidifying the mash). It is best not to try and mix them together.

[MashBag]

This might be quite good. Free Online session this week. With the chap from bru'n water.

https://www.crowdcast.io/e/water_chemis ... d/register

[cc986]

Thanks for taking the time to do that Eric. I do get what you are saying about BrewFather and had already decided that I would start using one of the others like Graham Wheeler's or Bru'n water.
P.S. My alkalinity test stayed pink!

Just be aware that different tools take different approaches to water treatment, often a cause of confusion!
Graham's calculator on here (amongst others) takes the historical approach of reducing alkalinity to the right amount for your grist and adjusting salts for changing the balance of the beer. The approach that has come out of the American homebrewing community, whose tap water can be problematic to brew with, takes a different approach (acidifying the mash). It is best not to try and mix them together.

Thanks foob4r.