How is PH effected by reverse osmosis?

[mblanks2]

Just finished the install of my new ro system and have finished the flush/discard of the first 3 to 5 gallons. Just pulled a sample as it was filling my storage tank and checked the ph. My tap water is about 6.5 to 6.8. What is coming out of the ro system is about 7.0 to 7.2. Is this normal? Assuming my PH meter is functioning alright.
TDS entering is 83, leaving is 0. Does the initial ph of the water play a real factor in mash and should I use the ro specs in bru'n water spreadsheet or make changes? Does this ph even matter? It looks like the ion's are the real game-changer. Is this correct thinking?
Thanks in advance for the input.

 

[mblanks2]

Just finished the install of my new ro system and have finished the flush/discard of the first 3 to 5 gallons. Just pulled a sample as it was filling my storage tank and checked the ph. My tap water is about 6.5 to 6.8. What is coming out of the ro system is about 7.0 to 7.2. Is this normal? Assuming my PH meter is functioning alright.
TDS entering is 83, leaving is 0. Does the initial ph of the water play a real factor in mash and should I use the ro specs in bru'n water spreadsheet or make changes? Does this ph even matter? It looks like the ion's are the real game-changer. Is this correct thinking?
Thanks in advance for the input.

Answered my own questions through additional research. Thanks, Martin.

 

[stonebrewer]

Answered my own questions through additional research. Thanks, Martin.

How about posting what you found then, in case others are curious? Cheers!

 

[mblanks2]

How about posting what you found then, in case others are curious? Cheers!

"The pH of the raw water used in brewing has only modest impact on the brewing process" from Water Knowledge on Bru'n Water website.

 

[z-bob]

The pH is kind of meaningless for pure water, just absorbing CO2 out of the air can cause its pH to drop.

 

[mblanks2]

The pH is kind of meaningless for pure water

Yeah, that's what I was concerned about but later answered my own questions. I should've just researched a little more before posting the question but with the new RO system I thought that they produced 6.0 PH and thought maybe there was a problem.

 

[Buckeye_Hydro]

The RO process strips most of the buffers from the feedwater.

 

[mabrungard]

While RO does strip out virtually all the buffering power of the water, dissolved gases from the raw water will still disproportionally permeate through the membrane and end up in the product water. If the raw water has a significant CO2 content, that will make it through into the product water and that can drive its pH very low. On the municipal level, we typically include air stripping as a component in the treatment train to allow that excess CO2 to exit the water before its put in the storage and distribution system.

On a side note, I had a client in Indiana with a small commercial RO system and they didn't know about this CO2 effect. They ended up ruining almost 200 barrels of beer before calling me in. That loss of beer and income ultimately took the brewery down.

 

[mblanks2]

While RO does strip out virtually all the buffering power of the water, dissolved gases from the raw water will still disproportionally permeate through the membrane and end up in the product water. If the raw water has a significant CO2 content, that will make it through into the product water and that can drive its pH very low. On the municipal level, we typically include air stripping as a component in the treatment train to allow that excess CO2 to exit the water before its put in the storage and distribution system.

On a side note, I had a client in Indiana with a small commercial RO system and they didn't know about this CO2 effect. They ended up ruining almost 200 barrels of beer before calling me in. That loss of beer and income ultimately took the brewery down.

With this in mind. I'm working on a scale of 30 gallons or less stored in an atmospheric tank. The raw water will stand covered for approximately 4 to 12 hours before use. Should there be any concern with this?
Also, in the Bru'n Water spreadsheet what are the ion concentrations represented for RO water based from?

 

[Buckeye_Hydro]

The pH of the water may change in that time. But without any buffers, the water will be very susceptible to pH change based upon anything you add to it.

 

[mabrungard]

The RO concentrations are an estimate taken from actual testing results on RO water. Your RO quality will vary, but probably not more than a couple of ppm. The main point is that it has very low mineralization, but is not pure.

 

[ScrewyBrewer]

Once you add the alkalinity back into the RO water the buffering should stabilize the pH.

 

[mblanks2]

Thanks for the replies. Just trying get a grasp on working with a clean slate. I've been using Bru'n Water for a few years but RO has raised allot of new questions. Looking forward to getting the new version.

 

[timsch]

I've been using RO water for a couple of years and have been happy with the results after adding minerals per style.

I have been typically drawing the water used for brewing the day before use and letting it sit in a covered but not sealed bucket. Should the water be sealed from the atmosphere, or is this short of a time not a concern?

 

[Buckeye_Hydro]

The reaction with air/co2 will start immediately, but I expect the reaction would be affected by temperature, air quality (co2 conc), water movement, etc. Test it with your pH meter over time and see.

Russ

 

[timsch]

So how do we relate the change in water pH to mash pH? It's the mash pH that matters.

 

[theheroguy]

While RO does strip out virtually all the buffering power of the water, dissolved gases from the raw water will still disproportionally permeate through the membrane and end up in the product water. If the raw water has a significant CO2 content, that will make it through into the product water and that can drive its pH very low. On the municipal level, we typically include air stripping as a component in the treatment train to allow that excess CO2 to exit the water before its put in the storage and distribution system.

On a side note, I had a client in Indiana with a small commercial RO system and they didn't know about this CO2 effect. They ended up ruining almost 200 barrels of beer before calling me in. That loss of beer and income ultimately took the brewery down.

Even if they didn't understand their base water shouldn't they have been taking PH measurements and adjusting the PH in the mash?

 

[ajdelange]

Yes, that story does seem a little unlikely. Possible, I suppose, if the permeate were kept under pressure but if it went to an HLT (or an atmospheric tank) any entrained CO2 should have escaped especially when the heat went on. Note that many craft operators do not check mash pH though I believe more and more do now that decent inexpensive meters are available.

At the home brew scale this should not be a problem as the major effects are likely to be absorption of CO2 from the air. As very little is actually absorbed the buffering is tiny as has been noted above.

 

[Menhir]

I've just installed an RO unit and would like to brew a batch of beer right away. I plan to test the RO water at Ward Labs to get get my numbers but don't want to wait several weeks before I brew. Does anyone have any numbers from tests that I could use to plug in numbers to Bru'n Water? I use well water that is run through a pH correction treatment system (calcite & manganese oxide) and then run through a water softener set for 2 grains hardness. I'm guessing that my RO unit will be primarily removing sodium.

 

[ajdelange]

I've just installed an RO unit and would like to brew a batch of beer right away. I plan to test the RO water at Ward Labs to get get my numbers but don't want to wait several weeks before I brew. Does anyone have any numbers from tests that I could use to plug in numbers to Bru'n Water?

pH 7, everything else 0.

I use well water that is run through a pH correction treatment system (calcite & manganese oxide) and then run through a water softener set for 2 grains hardness. I'm guessing that my RO unit will be primarily removing sodium.

Each calcium and each magnesium ion will have been replaced by two sodium ions so if your source water was hard then there will be a lot of sodium in the softener output.

The manganese dioxide is there for iron.
When you set your softener for 2 grains that is just to tell it how often to regenerate. It does not control the properties of the water it produces based on that setting.

 

[Buckeye_Hydro]

You set your softener for 2 grains? Hmm...

You mean you told the softener that your feedwater has 2 grains of hardness? That doesn't make sense. You wouldn't bother to soften your water if that was the case.

You also wouldn't set your softener capacity at 2 grains. Would be more like 32,000 grains.

So I'm not sure what you mean.

Russ

 

[afr0byte]

You set your softener for 2 grains? Hmm...

You mean you told the softener that your feedwater has 2 grains of hardness? That doesn't make sense. You wouldn't bother to soften your water if that was the case.

You also wouldn't set your softener capacity at 2 grains. Would be more like 32,000 grains.

So I'm not sure what you mean.

Russ

I'm guessing that was just a placeholder number.

 

[ajdelange]

You mean you told the softener that your feedwater has 2 grains of hardness? That doesn't make sense. You wouldn't bother to soften your water if that was the case.

That's 34 ppm as CaCO3 (13.6 mg/L). Many a salesman would be happy to sell you a system to remove that level.

 

[mabrungard]

and then run through a water softener set for 2 grains hardness.

I believe you have misinterpreted the use of that setting on your softener. A properly functioning ion-exchange softener will remove virtually all the divalent cations. The system would have to have a mixing valve to provide a treated water with more than ~0 hardness.

My softener has a setting that I program to tell the unit the hardness of the incoming water. That sets how often the softener is regenerated.

 

[Menhir]

I believe you have misinterpreted the use of that setting on your softener. A properly functioning ion-exchange softener will remove virtually all the divalent cations. The system would have to have a mixing valve to provide a treated water with more than ~0 hardness.

My softener has a setting that I program to tell the unit the hardness of the incoming water. That sets how often the softener is regenerated.

Yes, there is a mixing valve that mixes softened water with a small amount of the pH corrected water. The water treatment technicians adjusted the mixing so that it results in 2 grains hardness. This is mostly to keep my wife happy. She doesn't like the slimy feeling of showering in softened water. We had to install the pH correction system due to the fact that our low pH well water (pH 5.9) was eating up our pipes and faucets. Then we needed the softener to take out the high amount of calcium and manganese ions the pH correction unit added.

 

[Buckeye_Hydro]

Flomag/Corosex + Calcite cartridge/tank?

 

[ajdelange]

So I'm now thinking you have the typical (and absurd) neutralizer (dolomite bed tank) followed by a cation 'softener' with partial bypass of the softener. I have never heard of anyone doing the partial bypass but it is only sensible as if you do not mix in some bypass water the agressivity of the softened, neutralized water is higher than the water straight from the well. Some government entity was looking in to this a few years back but I haven't heard anything about it in years. When I mentioned this to the people that maintained my system there response was "Sir, we've been doing it this way for years". (I took the softener out and bypass the neutralizer when drawing brewing water as the neutralizer adds some alkalinity but as I RO everything that doesn't much matter).

 

[z-bob]

Was going to start a new thread to ask this, but I think it's on-topic here.
I've got a water report from the city. (the water here tastes good but is extremely alkaline; pH=7.5, HCO3 is over 300ppm)

Can I assume that the RO water that I buy from the machine at Walmart is pretty close to that water report with all the anions and cations divided by 10?

 

[Buckeye_Hydro]

That might give you a very rough cut at it.

 

[mabrungard]

I'd expect that the divisor would be closer to 20 for most RO water.

 

[z-bob]

I need to order that pH meter and stop guessing, don't I?

 

[Buckeye_Hydro]

Greatly affected by net driving pressure. So if you send the RO water to a pressurized storage tank - will likely be less than 10. To an atmospheric tank, and depending upon the membrane you're using, and some other factors, you might see a rejection rate up around 98%