Hard Water and High RA

Just got a home kit for measuring hardness and alkalinity. I'm closely following this article on water testing. I have a partial mash kit for a stout that I'm itching to brew.

Test Results:
GH - "General Hardness" (Ca+Mg): GH=28 (=498ppm)
KH - "Carbonates" (Alkalinity): KH=19 (=388 ppm)

The KH seems to be off the scale! Our municipal water is from a set of wells. I double-checked the test but it seems really high. OTOH, there is a lot of limestone in Indiana.

Using Kaiser's spreadsheet (same link above) it apportions the 498 ppm hardness to Ca 140 ppm and Mg 36 ppm. I am doing this right?

I'm also keeping an eye on this thread closely. But I haven't digested it completely yet.

So if I draw out the Ca=140, Mg=36, Alkalinity(ppm)=338 on the nomograph it puts me way off the high side of the mash pH scale. I think I'll have major RA problems when doing mashes, no?

BTW... The testing was for the water as it enters the house. Our water softener pulls out 90% of the (above) Hardness but none of the Alkalinity (just removes Ca/Mg cations). Likewise tried a Brita filter which drove the Hardness almost to zero but had only a minor impact on the Alkalinity. Clearly neither of these options will help.

That looks pretty similar to my water, although I have a bit less alkalinity and a greater amount of Mg. I sent my water to Ward Labs for analysis. The ratio of Ca/Mg isn't constant, and it can vary a fair amount.

For example here's my water:
Total hardness - 381
Ca - 74
Mg - 47
Bicarbonate - 440
Total Alkalinity - 360

You can see my Ca/Mg ratio is much different from what Kaisers spreadsheet is guessing for yours. Kaiser's guess is generally a good one, though.

Here's a thread where I went through the same thing you're trying to figure out. I ended up using lime softening, and I'm very happy with the results.

https://www.homebrewtalk.com/f128/estimate-water-profile-water-softener-251746/

The high RA is not a surprise in the land of hardness and alkalinity.

The home test kits are a handy thing to have, but they should be used to supplement a real lab testing result. You need the other ion results to give you a better idea of other ions that may create problems for brewing.

Enjoy!

Thanks for the link Nate, we've definitely got some of the same issues.

Martin, I've been looking over your Excel sheet and got a lot from the Water Knowledge sheet. Thanks! Between that and BrauKaiser's info I might attempt the lime treatment at some point. Would need to get a pH meter first though. And I appreciate you comment about getting a more detailed water test.

On the other hand, diluting with RO seems to be the quick and easy solution, right? I think that's going to be my first approach.

I know the water chemistry is key for the mashing process. But if I'm only doing partial mashes, how important is it to also treat the balance of the boil water?

dktoller said:

Would need to get a pH meter first though. And I appreciate you comment about getting a more detailed water test.

Click to expand...

I have one of those GH/KH aquarium test kits in addition to my pH meter. Really though, I seldom actually use the pH meter anymore. It might take a few times to practice it without a pH meter, but it's not really necessary to use the meter. As you add lime (don't forget gloves and goggles), the water will get cloudy and look like milk. As you keep adding lime to the water, it will look like milk when the curds and whey separate. Like this (only the water is clear, instead of yellow like the whey): http://farm5.static.flickr.com/4027/4472316077_a516657247.jpg

My water "breaks" at a pH between 12-14, which is high enough to knock out both Ca and Mg. Lower pH will only knock out the Ca, but you don't really want over 25ppm of Mg. Once the water breaks, I let it sit until it drops clear. That's usually 6-8 hours, but I usually let it sit overnight. I siphon off the water into another bucket at this point, and add acid. As you add acid, the clear water will get cloudy again as the Mg starts to precipitate out. It looks like gel, shiny and translucent, and kind of flaky.

I'll add the acid slowly while stirring until the water gets pretty cloudy again. I'll check the pH at that point, and adjust downward if necessary. It's usually around the high 8's or low 9's that it gets cloudy again. I'll let that settle for another 4-8 hours then siphon off again, leaving behind as much of the gel as I can.

The KH test will tell you the same thing the pH meter will. If you added enough acid, the KH test should register in the range you want for your mash water. If, after treatment, the KH is still too high, add more acid. High pH will mess up your results on the GH test too, so wait until after you've adjusted the KH down to the proper range before testing the GH to see how well you did on your softening.

Doing it this way you need to plan on a fair amount of racking loss. I start with 25 gallons if I'm planning on brewing a 10 gallon batch. I used to do just twice the batch volume, but I had a few times where I ran short of water, so now I make extra.

Lime is super cheap, like $2.50 at my grocery store, and I bought some phosphoric acid in bulk from dudadiesel.com. I mixed the acid down to 10% concentration, and it made like 8L of acid for $25. I don't think I've even used a liter of acid yet after softening at least 250 gallons, although I'm just about out of lime now. While it takes more time than just buying RO water, it was the most convenient and cost effective for me. Total cost on the test kit, the lime, rubber gloves, and acid was about $40, which breaks down to about $0.16/gallon so far, and I've only used 1/8 of the acid.

The acid traditionally used to reduce the pH of spilit treatment water is bicarbonate ion. One starts by computing the amount of lime necessary to remove the bicarbonate, adds all that to 1/3 - 1/2 of the water (which causes the Mg to precipitate) decants off that and then adds the remaining volume of untreated water to precipitate the bicarbonate from that. This obviously only gets 1/3 to 1/2 the Mg but that is usually enough.

The precipitate you see when you add phosphoric acid isn't a magnesium salt. It is calcium hydroxyl phosphate (apatite). You are pulling out the extra calcium you put in when you added extra lime to get the pH of the whole volume of water to 12. I don't see any problem with doing it this way. It doubtless gets most of the magnesium (as opposed to 1/3 - 1/2. Wonder what an analysis of the post treatment water would look like.

AJ - That's interesting about the apatite. I've been thinking about sending some more samples to Ward, one from treating the whole volume of water the way I've been doing it, and one from treating 1/2 the water then adding to 1/2 untreated.