Lower than calculated Mash pH - Is it Starsan or Something Else

[BrewKaiser]

My last two brews the Mash PH has been 2-3 points low. Historically, I've been very good about hitting my mash targets. I did a couple of things differently the last two sessions so it has me wondering.

Set UP:
I have a RO system and my tap water PH is 6.8. I use Bru'n water to calculate mash PH and am very consistent with strike and sparge volumes. I use 88% Lactic acid to acidify the mash as needed. I generally take my sample about 15 minutes into the mash and cool it to between 90-100*. My new meter has ATC

Process changes:
1) I took a 1-1/2 year brewing hiatus, so recently I broke the brewery down and gave all hoses, tri-clamps, gaskets, and valves a good soak in PBW. Afterward I rinsed well and then ran everything through Starsan (1 oz per 5 gal solution - maybe a little more than 1 oz). Drained the hoses, but still wet.

2) I started pre-soaking/dissolving my brewing salts in a jar of warm water about 20-30 minutes before dough in. Not acid, just Gypsum, Baking Soda, Calcium Chloride, Epsom Salt. The acid I add directly to the entire strike volume after pouring salts and before adding grain.

3) New pH meter. Calibrated per instructions.

Questions:

1) Given how many hoses, valves, Tri-C clamps and gaskets I have I was wondering if the residual Starsan is having an affect on the mash pH. Admittedly it's silly that I even worry about sanitizing on the cold side of the process at all. Just dumb OCD.

2) Could pre-soaking/dissolving the brewing salts somehow affect the utilization. I would think not.

3) Whats the shelf life of brewing salts and Lactic Acid? Some are a few years old now. The lactic acid is at least 4 years old. I wonder if over time it evaporates and is in higher concentration than 88%. Usually only need .2 or .3 ml so again I wouldn't think this is the issue.

 

[doug293cz]

What pH meter are you using? Do you verify the calibration at the end of you mash against 4 & 7 pH calibration solutions? Are you actually using acid and baking soda at the same time? If so, they just work against each other (baking soda raises pH and acid lowers it.)

Brew on

 

[postalbunny]

You shouldn't worry about residual sani, that won't do much. As far as age on the chems... they should be fine if properly stored. If you're worried about the lactic you always measure it, or just buy some new for piece of mind. The chems may have taken in water if stored in a non-airtight container (air can leak into zip lock bags). Like CaCl has a tendency to absorb outside moisture and brick up. That could throw off your measurements as far as weight in grams/oz if there is some extra water content. but regardless of salts, even with "no salts" in RO water you shouldn't be seeing a 4.x or 6.x reading.

Did you mean 2-3 points as in 5.3X where "X" is the number fluctuating, or 5.X? If you're getting a reading in low 4.x or high 6.x range i'd suspect that meter needs testing and calibration. You say your RO is 6.8 so i assume the meter is reading correct enough at ph7, but maybe a ph4 calibration is in order.

Also... you say you cool it to 100°F, most books are telling you the mash ph "at temp"... meaning at 150ish. By cooling the mash you will get a different ph reading. If i recall mash temp ph of 5.2-5.4 is close to 5.5-5.8 at room temp. If you're measuring at 100°F then you're prob somewhere in-between.

 

[BrewKaiser]

What pH meter are you using? Do you verify the calibration at the end of you mash against 4 & 7 pH calibration solutions? Are you actually using acid and baking soda at the same time? If so, they just work against each other (baking soda raises pH and acid lowers it.)

Brew on

Using:
Apera Instruments AI311 PH60 Premium Waterproof pH Pocket Tester, Replaceable Probe, ±0.01 pH Accuracy, -2.00-16.00 pH Range

I do not verify against 4 & 7 pH. I calibrate the night before.

I typically do not use baking soda.

 

[BrewKaiser]

Did you mean 2-3 points as in 5.3X where "X" is the number fluctuating, or 5.X? If you're getting a reading in low 4.x or high 6.x range i'd suspect that meter needs testing and calibration. You say your RO is 6.8 so i assume the meter is reading correct enough at ph7, but maybe a ph4 calibration is in order.

As in 5.09 versus what I was targeting at 5.4

o... you say you cool it to 100°F, most books are telling you the mash ph "at temp"... meaning at 150ish. By cooling the mash you will get a different ph reading. If i recall mash temp ph of 5.2-5.4 is close to 5.5-5.8 at room temp. If you're measuring at 100°F then you're prob somewhere in-between.

My previous meter did not have ATC so had to measure at 70*-ish. New meter is has range up to 122*. My two most recent mash pH readings were 5.01 and 5.09. So low.

 

[doug293cz]

.

Using:
Apera Instruments AI311 PH60 Premium Waterproof pH Pocket Tester, Replaceable Probe, ±0.01 pH Accuracy, -2.00-16.00 pH Range

I do not verify against 4 & 7 pH. I calibrate the night before.

I typically do not use baking soda.

What is your calibration procedure? Most of the recommendations I have seen is to calibrate shortly before use (less than a couple of hours at most.)

Brew on

 

[postalbunny]

to be honest, i cant' imagine you'd be that far off even you haven't calibrated in a several months. A 5.09 vs 5.4 is pretty large.

I use a Hanna phep5 and read with the probe directly in the mash tun. I usually get 5.2-5.3, when i get below 5.2 and correct I see the correction take affect in 10-15mins. I've read that measurements should be done at 'room temp' even though ATC may be present, but have been making good beer this way so I have not gone the extra step of trying to ice bath samples.

Next brew day i'll see if I can grab a sample and see what i get for 100degF and also room temp vs mash temp.

 

[BrewKaiser]

.

What is your calibration procedure? Most of the recommendations I have seen is to calibrate shortly before use (less than a couple of hours at most.)

brew on

I calibrate the night before per calibration procedures. New probe and previous always calibrated. Then store in storage solution until next day.

 

[BrewKaiser]

to be honest, i cant' imagine you'd be that far off even you haven't calibrated in a several months. A 5.09 vs 5.4 is pretty large.

I use a Hanna phep5 and read with the probe directly in the mash tun. I usually get 5.2-5.3, when i get below 5.2 and correct I see the correction take affect in 10-15mins. I've read that measurements should be done at 'room temp' even though ATC may be present, but have been making good beer this way so I have not gone the extra step of trying to ice bath samples.

Next brew day i'll see if I can grab a sample and see what i get for 100degF and also room temp vs mash temp.

I pull sample from sample valve (return side of pump) and either stick in the freezer next to my rig for a few minutes or rinse outside of sample jar with cold water. Small sample cools quickly.

I did not make any adjustments during the mash since I hadn't ruled out the pH meter being faulty. I feel too low of a mash pH is better than too high.

 

[btcost]

Are you measuring the RO water pH or just assuming 6.8?

Measure to verify.

I like to calibrate immediately before measuring. And I always measure @ room temp. Even though I have an ATC pH meter.

Maybe switch to 10% phosphoric acid you will need more, but it’s much easier to measure 4ml then .3 ml. Imhop.

I use both in my brewery. Depending on what I’m brewing I switch it up.

 

[mongoose33]

For those who don't want to "ice bath" or put a sample in the freezer to cool it....

What I do--read this on HBT a couple years ago--is to keep small glass...glasses/beakers in my freezer. I pull the sample and put it in the thick one. It's cold from sitting in the freezer. I let it cool that way, often transferring to another I've pulled out of the freezer. I stir using the thermometer, and it takes just a couple minutes to cool this way.

Here's a pic. The glasses on the right are whisky glasses, of which, sadly, I only have one remaining. The other was dropped by a clumsy homebrewer...



*******************

For @BrewKaiser: how do you calibrate a pH meter without using calibration fluid? I use the 4.01 and 7.00 fluids to calibrate. Is there another easier way?

 

[chickypad]

Using:
Apera Instruments AI311 PH60 Premium Waterproof pH Pocket Tester, Replaceable Probe, ±0.01 pH Accuracy, -2.00-16.00 pH Range

I do not verify against 4 & 7 pH. I calibrate the night before.

So how are you calibrating then? The instruction manual for that probe says to use the included 4 and 7 pH calibrations solutions.

 

[BrewKaiser]

So how are you calibrating then? The instruction manual for that probe says to use the included 4 and 7 pH calibrations solutions.

Oops. I just saw my typo. I calibrate first with 7.0 solution then the 4.0 per the instructions. I rinse with distilled water between calibrations and dry the probe per instructions.

 

[btcost]

Suggestions:

Get new acid (it’s cheap)

Get both 10% and 88%

Personally I use 10% or acid malt in the mash as I usually need so little to get my mash ph in line.

I use 88% in the sparge water to get it to 5.5.

Brew again and see what happens. You are clearly an experienced brewer, so you just need to brew!

 

[cooper]

Agree with btcost! Just brew up a few more batches to get the hang of your process again.