No-Spage Mash pH Way Off

[trav77]

Hi folks

I recently switched from a 3v batch sparge system to BIAB no-sparge. Yesterday I brewer an APA and was way off my mash pH as predicted by Brun Water (on my old system I found Brun Water to be pretty accurate although I have changed many variables since then).

Used RO water, full volume mash/no-sparge, 1 tsp each CaCl and CaSO4, 2.8% acid malt.

BrunWater predicts pH of 5.3 and I got 5.7 at 15 min into the mash at room temp with a freshly calibrated pH meter and brand new standards.

Thoughts? Anyone doing full-volume/no-sparge/BIAB and having to add more acid than calculators suggest?

Anyhow... here's the grain bill and Brun Water info below:

Recipe Specifications
--------------------------
Boil Size: 7.00 gal
Post Boil Volume: 6.25 gal
Batch Size (fermenter): 5.50 gal
Bottling Volume: 5.00 gal
Estimated OG: 1.055 SG
Estimated Color: 7.2 SRM
Estimated IBU: 37.4 IBUs
Brewhouse Efficiency: 70.00 %
Est Mash Efficiency: 76.4 %
Boil Time: 60 Minutes

Ingredients:
------------
Amt Name Type # %/IBU
1.00 tsp Calcium Chloride (Mash 60.0 mins) Water Agent 1 -
1.00 tsp Gypsum (Calcium Sulfate) (Mash 60.0 mins Water Agent 2 -
4500.00 g ESB Pale Malt (Gambrinus) (3.5 SRM) Grain 3 84.1 %
450.00 g Golden Naked Oats (10.0 SRM) Grain 4 8.4 %
250.00 g Victory Malt (25.0 SRM) Grain 5 4.7 %
150.00 g Acid Malt (3.0 SRM) Grain 6 2.8 %

Mash Schedule: BIAB Default
Total Grain Weight: 5350.00 g
----------------------------
Name Description Step Temperat Step Time
Saccharification Add 7.86 gal of water at 157.5 F 152.1 F 60 min

Brun Water details:

 

[Silver_Is_Money]

Have you tested the alkalinity of your RO water? My first guess would be that your RO water has a fair amount of it.

 

[mabrungard]

Did you have only one pH reading? You should monitor pH throughout the mash since it does vary during the mash.

In addition, were the minerals added to the water and mixed thoroughly or to the mash and then mixed in? It makes a difference.

 

[mabrungard]

Good point about the RO water not really being as pure as expected. Did you check the RO with a TDS meter to assure that the TDS was nice and low?

 

[trav77]

Have you tested the alkalinity of your RO water? My first guess would be that your RO water has a fair amount of it.

No I haven't checked. That would be my first guess as well. Any recommendations for an inexpensive way to test?

 

[trav77]

Did you have only one pH reading? You should monitor pH throughout the mash since it does vary during the mash.

In addition, were the minerals added to the water and mixed thoroughly or to the mash and then mixed in? It makes a difference.

Just the one pH reading although I'm aware it does change as the mash progresses. At what point in the mash would You expect the target reported in BrunWater?

I added the CaCl and CaSO4 once the strike water was heated. I guess it is possible that they were not dissolved as well (I usually add to cold water the night before... So different process there). Also the false bottom does impede stirring a bit so that could factor in as well.

If my numbers in BrunWater look reasonable and there's no technical reason why I I got high mash pH then I'll have to look to these parts of my process with the new system.

 

[trav77]

Good point about the RO water not really being as pure as expected. Did you check the RO with a TDS meter to assure that the TDS was nice and low?

Nope. Are cheapo TDS meters reliable enough?

Eg
https://www.amazon.ca/gp/product/B00DQ203YW/?tag=skimlinks_replacement-20

 

[Silver_Is_Money]

A 'KH' test drops kit will do it, but in actuality it's pretty hard to pin down a good reading on RO water via this simple and inexpensive method.

A TDS meter may tell you something, but it will not isolate alkalinity. You could take a sample to a local store that sells water softeners and bottled RO and distilled water, and they will gladly do a free TDS meter test on it (or at least my local store does this gladly). If it comes back at greater than about (as a first guess) 20 TDS, it may be suspect of having some alkalinity that is sufficient to begin moving mash pH's upward.

 

[ajdelange]

A 'KH' test drops kit will do it, but in actuality it's pretty hard to pin down a good reading on RO water via this simple and inexpensive method.

Accurate measurement of low alkalinity is fairly simple to achieve even with a drop count test kit. In the Hach alkalinity test kit, for example, 1 drop of acid is equivalent to 10 ppm as CaCO3. Want to measure accurately at the 6 or 7 ppm level? Use 10 times the volume of sample, add 10 times the amount of indicator (so color at end point will be the same) and add drops. Each drop is now equivalent to 1 ppm as CaCO3. This obviously burns through your indicator pretty quickly but if you have a pH meter you can titrate to pH 4.5 as indicated by the meter.

But in reality it doesn't matter very much whether the alkainity is 3 or 5 or 10. Knowing that it is less than 10 is sufficient as that indicates that water alkainity is insubstantial compared to grain alkalinity.

 

[Silver_Is_Money]

Would it be a fair first guess to presume that for typical RO water 1/2 to 2/3 of TDS is potentially pointing to alkalinity?

 

[ajdelange]

If the water has no temporary hardness then none of the TDS is alkalinity but that would be unusual so I suppose that where the TDS measurement is low it's probably OK to call half of it attributable to bicarbonate and as 61 mg/L bicarb causes about 50 ppm alkalinty it's often going to be at least approximately true that alkalinity is half the TDS.

 

[Silver_Is_Money]

Thanks AJ! For the OP this should be the easiest and least expensive road to ballparking his RO waters alkalinity.

 

[trav77]

Thanks guys. I discovered two things since. The first is that my RO filter was not quite plumbed in correctly so I was effectively just using my house water. I have a lab analysis on it which is:

Ca: 60
Mg: 19
Na: 16
HCO3: 165
SO4: 19
Cl: 25

TDS = 162
Alkalinity = 135

When I put that into Bru'n Water for my last batch I get an estimated mash pH of 5.6 which is pretty close to my measured pH of 5.7. OK so that's just my screwup.

Now that my RO filter is hooked up properly, I've measured TDS and it's still at 120 (~ 46% of unfiltered). Not really pleased with that performance of the RO filter...

Anyways, can I assume then that my cations, anions, and alkalinity would therefore be directly proportional to the reduction in TDS by filtering? I.e. I can use values that are 0.46*x from my lab report?

In that case, the water still is not ideal. Bru'n Water estimates I would need 5% acid malt to get to pH 5.3 on this APA. Playing around with it some more suggests I would need up to 7% on an average light lager, helles, pils, etc.

Anyone used acid malt at that high a ratio? The point of the RO filter was so that I didn't have to buy water to dilute!

 

[ajdelange]

Thanks guys. I discovered two things since. The first is that my RO filter was not quite plumbed in correctly so I was effectively just using my house water. I have a lab analysis on it which is:

Ca: 60
Mg: 19
Na: 16
HCO3: 165
SO4: 19
Cl: 25

TDS = 162
Alkalinity = 135

When I put that into Bru'n Water for my last batch I get an estimated mash pH of 5.6 which is pretty close to my measured pH of 5.7. OK so that's just my screwup.

So Bru'n is vindicated and we can go on from there.

Now that my RO filter is hooked up properly, I've measured TDS and it's still at 120 (~ 46% of unfiltered). Not really pleased with that performance of the RO filter...

While you cannot be sure that your lab used the same translation of conductivity to TDS (why can't they just give us the conductivity?) so that you can't really compare your meter's reading to the report's TDS 120 is way too high. Your RO membrane must have leaks between the brine and permeate sides. Be sure your unit is plumbed properly and then replace the membrane cartridge.

Anyways, can I assume then that my cations, anions, and alkalinity would therefore be directly proportional to the reduction in TDS by filtering? I.e. I can use values that are 0.46*x from my lab report?

A properly functioning membrane may reject 99% of sodium but only 95% of bicarbonate and as the individual ions have different mobilities assuming the rejection of an ion is the same as the ratio of conductivities (ratio of TDS from the same meter) won't give you a very accurate profile for the permeate. But if alkalinity is 135 and knocked down by 95% to 6.75 and sodium by 99% from 16 to .16 it doesn't much matter as the ion concentrations are all low enough that they can be substantially in error (percentage wise). Suppose the permeate bicarbonate were really 4 and the sodium were really .3. Would that make much difference?

That's rather rambling but what it says (or tries to say) is yes, just use the TDS ratio to scale ion concentrations.

In that case, the water still is not ideal. Bru'n Water estimates I would need 5% acid malt to get to pH 5.3 on this APA.

The rule of thumb (from Weyermann's so perhaps we might want to recognize that it might fit their product better than other peoples) is 1% for each desired 0.1 pH shift. Thus to get to 5.3 from 5.7 you would need about 4%. But 5.3 is a rather low target. Most would shoot for 5.4 - 5.5 and thus use 2 - 3%.

Playing around with it some more suggests I would need up to 7% on an average light lager, helles, pils, etc

Something fishy here. Generally 2 -3% suffices for those styles.

Anyone used acid malt at that high a ratio? The point of the RO filter was so that I didn't have to buy water to dilute!

I believe Weyermann publishes a recipe for a pesudo Berliner Weiß that uses 8% (IIRC and I often don't) Sauermalz. Consider that when pondering this question.

 

[Buckeye_Hydro]

Now that my RO filter is hooked up properly, I've measured TDS and it's still at 120 (~ 46% of unfiltered). Not really pleased with that performance of the RO filter...

Something is still not right here. If you'd like, give us a call when you are in front of the system and we can troubleshoot the RO over the phone. Should only take 5 minutes. We'll be in the shop all day today (Sunday).

Dave
513-312-2343

 

[trav77]

Something is still not right here. If you'd like, give us a call when you are in front of the system and we can troubleshoot the RO over the phone. Should only take 5 minutes. We'll be in the shop all day today (Sunday).

Dave
513-312-2343

Thanks for the offer Dave. Mine's not from Buckeye but if you or someone else wants to confirm that my plumbing is OK then great!

Might be easier to give you a diagram. This is the model:

https://www.homedepot.ca/en/home/p....ng+Materials&gclid=COvy5rGdkNICFQyoaQodrIcPPw

The first image shows the installation diagram from the manual. I did not want to plumb it in with the faucet or storage tank so I plumbed it like the modified diagram in the 2nd image. In a nutshell, just made it a simple inline series. I removed the backflow valve and plugged the 2nd outlet of the RO membrane with a threaded brass plug.

 

[ajdelange]

Well that certainly explains it. The incoming flow is on one side of the membrane with the outflow you plugged. Having done that there is no place for the rejected ions to go so the concentration builds up in the brine channel until it is so high that even 90% rejection means high concentration in the permeate side. Remove that plug and let the water from it flow to waste. If you haven't ruined the membrane things should start to work.

 

[trav77]

Well that certainly explains it. The incoming flow is on one side of the membrane with the outflow you plugged. Having done that there is no place for the rejected ions to go so the concentration builds up in the brine channel until it is so high that even 90% rejection means high concentration in the permeate side. Remove that plug and let the water from it flow to waste. If you haven't ruined the membrane things should start to work.

Thanks AJ. RO membrane 101 I guess.

I'll give it a shot later today. Hopefully the membrane is still OK.

 

[Buckeye_Hydro]

AJ is right on the money. Unplug that port. You'll also need a flow restrictor. See if you can find your original flow restrictor - if not we have them for only $4. The flow restrictor should be matched to the gpd capacity of your RO membrane, and it is installed in the concentrate tube.

Also - never use brass of any metal fittings (other than stainless) where they will contact RO water.

Also - I'd get rid of the inline taste and odor ("post filter") filter - that was installed on your original configuration to remove the taste and odor the RO water can pick up from the poly bladder inside the pressure tank. With the pressure tank out of the picture, the taste and odor filter is not needed.

What sediment filter and carbon block are you using?

Do you have chloramines in your tap water? If so, it will make sense to put that second carbon housing to use.

Russ

 

[trav77]

Thanks for all the advice guys... I really appreciate it. It's up and running now. Reading 4 ppm TDS.

View attachment ImageUploadedByHome Brew1487131148.871280.jpg

 

[ajdelange]

That's the kind of resolution we like to see!

 

[Silver_Is_Money]

Indeed a happy ending. 4 ppm TDS is phenomenal for RO. A lot of the distilled water brands I've checked (via my Hanna MicroSeimens [uS/Cm] meter) come in noticeably higher than that. You are approaching DI.

I'm at 58 ppm TDS on my RO (actually measured as 116 uS/cm), but given that I started with well water at 640 TDS (actually 1,280 uS/cm), I can accept that 58 sounds good by comparison, given that my RO unit is a budget model.

 

[Buckeye_Hydro]

Indeed a happy ending. 4 ppm TDS is phenomenal for RO. A lot of the distilled water brands I've checked (via my Hanna MicroSeimens [uS/Cm] meter) come in noticeably higher than that. You are approaching DI.

I'm at 58 ppm TDS on my RO (actually measured as 116 uS/cm), but given that I started with well water at 640 TDS (actually 1,280 uS/cm), I can accept that 58 sounds good by comparison, given that my RO unit is a budget model.

You should be able to get better quality RO water than that, given your feedwater TDS. If you'd like help troubleshooting, feel free to give us a call.

Russ
513-312-2343