Struggling with filtered water being corrosive.

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
Moxiechef
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#1: Post by Moxiechef »

Here's a pick of my water analysis prefiltered. I've been using a BWT BestMax Premium but it's causing corrosion, little blue green floaties in the brew boiler water. I haven't sent off the filtered water for testing but my in-house test show a drop to 95 ppm TDS and 6.4 pH.

I've got the filter set to the highest bypass setting.

When I look at my unfiltered numbers compared to the La Marzocco water sheet, things look acceptable except the TDS is 158 and they recommend a max of 150. When you put my numbers into their online calculator, it show "Scale will form".

Thoughts on a solution?




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homeburrero
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#2: Post by homeburrero »

Moxiechef wrote:I've been using a BWT BestMax Premium but it's causing corrosion, little blue green floaties in the brew boiler water.
I'm clueless as to what those blue-green floaties are. Copper corrosion would produce blue green deposits or add a blue-green tinge to water when dissolved, but not normally floating. Others with experience with that machine (a GS3?) might know, or perhaps LM support.

Your tap water analysis looks like a reasonable water for that BWT premium, because it has pretty good alkalinity and the chloride is not high. Your measured pH of 6.4 on the filtered water does not look good, but pH can be hard to measure. If it were me I'd give the treated water a GH and KH test and use a bypass that keeps the KH of the treated water at 40 mg/L or more. You can use an easy and inexpensive API GH & KH drop test kit with a stretched sample -- instead of a 5 ml sample find a container that holds 10 ml, then each drop corresponds to 8.9 mg/L as CaCO3.


P.S.
If it were me choosing a filter for this water I think I'd just go with a conventional softening filter, but I'm a non-beleiver in the 'precious magnesium' promoted by BWT. A conventional softener would not change your pH, would reduce the hardness (calcium and magnesium) to very low (non-scaling) levels, and would keep that 75 ppm bicarbonate alkalinity. It would increase your sodium by maybe 40 ppm.
Pat
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Ssspressso Luva
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#3: Post by Ssspressso Luva »

Curious how you got your unfiltered numbers? If from a lab, would you kindly share? Thank you.

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homeburrero
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#4: Post by homeburrero »

Ssspressso Luva wrote:Curious how you got your unfiltered numbers? If from a lab, would you kindly share? Thank you.
I'm not Moxiechef, but it looks to me like that report he posted was from an analysis by Ward Laboratories. (See this one, for example: St. Louis Water Report and Plumbing Thoughts, which has an identical report format.)
Pat
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DaveC
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#5: Post by DaveC »

pH of 6.5 is the same as milk, so I doubt there will be any significant corrosion, especially considering the materials involved. If you are really concerned, put in a very small amount of Bicarb as an effective buffer agent. You would only need a tiny amount...less than you could ever taste. Obviously if it's direct plumber you can't do that.