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High pH in HLT/CLT

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  • dick murton
    replied
    I commissioned one for a large brewery many years ago, but we built it from scratch, though of course I am sure someone will make a suitable dosing system.

    For a start, they had extremely consistent water - borehole, which made control much easier. So we used proportional dosing, which meant a fixed speed positive displacement pump for the acid (we used sulphuric) with a flow switch on it to check it pumped, flow meter on the water supply, to control the operation of the acid dosing pump, with an in-line mixer after the dosing point and a pH meter downstream to check the operation was OK. Plus alarms to the brewhouse automation. Because of the large amounts of CO2 produced, this was followed by a degassing tower. So an automated system is possible, but not cheap, and if you have variable water quality, the system is likely to be more complex due to the additional controls. You should be able to get away using manual variable dosing pump output if you have a pH meter and alarms on the pH.

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  • BuckeyeHydro
    replied
    Have you considered a small dosing pump?

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  • shariftaleb
    replied
    Has anyone come across an inline dosing system to reduce water pH into the water filter or HLT. Our water pH is 7.8-8.2 depending on the time of year. We have been dosing the HLT with phosphoric and it has reduced astringency. We would like to find a way to automate this process

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  • WaterEng
    replied
    Jwalts,

    While Milwaukee is on Lake M, it depends where in the city a user is, if their water is from the lake. The Great Lakes Compact now requires that Great Lakes water stay within the Great Lakes basin and Milwaukee and hundreds of other municipalities have had to replumb their utilities and water supplies to meet that requirement. Suburbs away from the lake could now have really crappy groundwater supplies that are hard and alkaline. Your experience with chalky precipitation and sedimentation is not a surprise.

    I haven't explored the saturation limit of magnesium phosphates, but I'm guessing that it is much higher than that for calcium phosphates and isn't a problem.

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  • dick murton
    replied
    A bit slow to respond, but the simple answer is no. I've not seen anything published, though admit to not having searched, and have never looked into it on my own behalf - I wouldn't have made a mess of the earlier responses if I had (I hope!!).

    I would be interested if anyone does have any sort of information which differs from this source https://www.aqion.de/site/191 which gives the pH of CaCO3 solution as 9.91 at concentrations of 1 mM 10 mM 100 mM per litre (valid for standard conditions at 25°C, 1 atm)

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  • jwalts
    replied
    WaterEng,

    Going on a tangent and assuming that carbonate alkalinity is causing the pH increase - i.e. not to say that the carbon filter media isn't the problem - wouldn't that imply that a lot of calcium is likely present? If the carbonates were to originate primarily from magnesite or even dolomite, I'd be curious how the precipitation of magnesium phosphates would compare with calcium phosphates. Anyway, precipitation of calcium phosphates with phosphoric-treated water is certainly a problem with the groundwater in south-central Wisconsin (total alkalinity of ~300 mg/L as CaCO3) - and I've experienced it personally. Not that I've quantified the loss of calcium, but dealing with any chalk-like deposit on brewing equipment is a pain.

    That said, I'd expect Milwaukee water to come from Lake Michigan and contain a lot less calcium carbonate. So I'd agree that my concern about phosphoric acid could be overblown for hophead34, but it's hard to say for sure without seeing a water report. That's why I included the "if the carbonate alkalinity is high enough" qualifier. With that in mind, I'd be interested to know how much calcium carbonate would be needed to raise the water's pH from the mid 7s to 9ish during heating. Is that something you've looked into?

    Joe

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  • WaterEng
    replied
    Is your carbon filter using acid-washed media as it should be? Standard carbon media can have a high pH following manufacture and it can impart an elevated pH to the water passing through it. The acid-washing helps neutralize that problem. It sounds like you may need to perform an acid rinse on the carbon unit to help neutralize the media.

    Regarding apatite formation, the calcium concentration in the water will need to be fairly high for a phosphoric acid addition to create that precipitate. The concerns about loss of calcium from phosphoric acid addition are overblown.

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  • jwalts
    replied
    Dick, you beat me to this exact response! The only thing I would add is that if the carbonate alkalinity is high enough to cause this issue, using phosphoric acid would probably result in deposits of calcium/phosphate solids such as apatite instead of calcium carbonate. I've had good results with lactic acid.

    Joe

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  • dick murton
    replied
    My previous suggestion - I think I got it the wrong way round. Calcium bicarbonate has a lower pH than calcium carbonate. On heating, the calcium bicarbonate decomposes to calcium carbonate and CO2 - so the pH rises.

    So the way I would treat it would be to add some acid - food grade sulphuric if it isn't going to screw up the rest of your mineral composition, otherwise possibly phosphoric or lactic. I would expect you to be building up hard water scale on the water side of the heat exchanger plates as well. So you will eventually get poor heat transfer. So you will probably have to acid wash the water side of the PHE periodically.

    The carbon filter is for chlorine / chloramine removal mainly, not hard water ion removal.

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  • hophead34
    replied
    Following up on this topic, which I started way back when we opened in September. Seems like 6 years ago but it's only been 6 months. I'm sure you can relate.

    Anyway, we are STILL experiencing high pH levels in our HLT (which is what we are using for our brewing water, hence the main issue here). So far we've been utilizing small amounts of Wyermann sour malt to get our mash pH levels in line but sparging with high pH water sucks, and generally we'd just like to solve this problem anyway.

    The HLT system is a standard non jacketed stainless tank. Created by Sprinkman. It utilizes a stainless-piped recirculation pathway that routes through a steam fed HX (steam on one side of the plates/HLT water passes through the other side). Everything should be up to spec and it (by all accounts) is well made and still brand new.

    The water goes into the HLT at a standard city water pH in the 7.5-7.8 range usually. If we let the water just sit in the HLT without recirculating it stays about the same. We've seen a slight amount of upward creep but maybe 0.10-0.20 at most.

    If we turn on the steam and run the recirculation to heat the water, we see a gradual rise in pH over a span of about 2-24 hours to levels as high as the low 9s. Wowza.

    -Based on feedback in this thread we've back flushed our carbon filter just to be safe. That said the water comes in at 7.5 so not sure how this would affect the situation anyway.
    -We do not use water softening measures on the water that enters the HLT. We do use a softener on the water supply to our boiler
    -We have had Ecolabs perform several analysis runs on our water. Nothing out of the ordinary.
    -I had Alfa Laval stop in and inspect the HX plates to see if we were experiencing steam creep into our HLT water. They ran a dye test and we even replaced all the plates and gaskets. Nothing changed.

    At this point we are kind of at a loss. The water is picking up OH- ions or something along the way during recirculation/heat up and we have no idea where. Figured I would ask this thread one more time in case someone has an idea.

    Thanks again!

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  • dick murton
    replied
    High calcium carbonate content dissolved in the water, which is then reacting with CO2 to create bicarbonate and thus increase the pH ????? Think I'm clutching at straws here, but it is the only thing I can think of.

    What is your water analysis??

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  • Jeremy N King
    replied
    Do you have a new carbon filter? If so, how extensively have you backflushed it?

    Also, try blending barley with water in a small proportion similar to what your normal water:grist ratio is and test pH there.
    Last edited by Jeremy N King; 09-17-2019, 11:50 AM.

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  • Weehe
    replied
    Going off the water softener topic. Any chance the lines running to the brewhouse are not softened water but the rest of your facility is?

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  • Starcat
    replied
    Interesting....

    Originally posted by jwalts View Post
    Is your brewing water softened? Madison-area water, which is extremely alkaline, is usually in the mid-7s but can increase into the 9s when softened. If somebody (often not the brewer in these instances) included a fancy water softening system in the build-out, you may be able to flip a few valves to bypass it.

    Joe
    This is a very interesting subject. While the Alkilinity of Salt Softened water is usually notably higher, I have never encountered a PH change as is being described.
    I would like to hear the water chemistry experts chime in on this one.
    Also total alkilinity and PH are not the same thing.
    There are a major lot of contradictory publications on dealing with salt softened water that defy fully what field experience has shown to be the case. Its a labyrinthe, and as thus full of experts that cannot agree on many points and must be taken on a case by case basis with heavy coordinated analyses carried out. When you are salt softening VERY hard water such as back in Texas, you naturally end up with a high amount of sodium bicarbonate in the finished water. This is what gives salt softened water the characteristic slick feel.

    Star
    Last edited by Starcat; 10-13-2019, 10:25 AM.

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  • jwalts
    replied
    Is your brewing water softened? Madison-area water, which is extremely alkaline, is usually in the mid-7s but can increase into the 9s when softened. If somebody (often not the brewer in these instances) included a fancy water softening system in the build-out, you may be able to flip a few valves to bypass it.

    Joe

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