Low Mash Ph

[Scooby]

My brews seem to have a low mash Ph recently, falling in between 4.7-5.0 I've tested my water and been using a total alkalinity of 214mg/l CaCO3, I add 0.9ml CRS/l to leave a residue 50mg/l CaCO3. Nothing else is added to the mash but I add other salts to the boil. I've done many brews where the Ph registered 5.3 every time and haven't changed anything else. The hardness is 294mg/l CaCO3 and the other minerals in the water that I know of are:

Sodium 13.6mg/l
Chloride 37.5mg/l
Sulphate 19.4mg/l

I've checked the alkalinity of the supply water on occasions but nor recently, I've also checked the residue after treatment and have found it very close. I decided to make up a new 1/40 solution as I have a new batch of CRS, I was hoping the answer would be a lower alkalinity but it turned out to be higher at 243mg/l CaCO3 which would push the CRS addition up even more.

Do indicator strips drift over time and Is there any way of checking them with something of a known alkalinity? I've had the strips over 2yrs.

I'm tempted to reduce the CRS addition until the Ph is correct but that seems wrong as I'm confident that the alkalinity test I did is sound.

[Scooby]

Most have been straight forward and if there has been specialty malts they amount to 1 or 2% only, the last brew was pale, crystal and amber malts with 0.9% chocolate.

Dough in takes about 3-5mins, lid on for 5mins then stir and check for dry spots and temperature then just dip straight in the tun.

[Scooby]

You should be getting the correct mash ph with ~20-30 mg/l caco3.

I work out my CRS addition to leave a residue of 50mg/l caco3 to be on the safe side and not overdose.

Are you using methyl orange or the salifert test kit ?

Methyl orange.

Has the reagent or indicator become contaminated, do you ditch any excess reagent/indicator or return it to the bottle ?

I return the indicator to the bottle and although I keep the pipette clean and just for that it could cause contamination.

Are you testing the water before each brew ? It may change daily.

Are you testing the alkalinity of the water after you have treated it, I can't recall myself hitting the alkalinity spot on in the first addition ?

I don't test before each brew but I do test after treatment, if the result is between 20-50mg/l caco3 I accept it, 80% of the time I have to make small adjustments.

Contamination of the indicator could be the cause and I know the water can change daily but not by massive amounts. I have always added 0.9ml/l as the initial treatment and as mentioned more often than not had to make adjustments but nothing prior to taking the pH readings has set the alarm bells ringing, all seems to be normal until I dip the strip but it's now the norm to see less than 5.0

[Scooby]

Contamination of the indicator could be the cause and I know the water can change daily but not by massive amounts.

It can depending on your water supply, if it comes from more than one source or from bore holes it can vary a lot. Ideally you wouldn't return the reagent back to the bottle incase of contamination. If it's the original reagent, acid can degrade over time, it may be time to make some fresh if its still the original batch or it's getting on a bit.

Sorry Chris, I return the methyl orange to the pot after 5 or 6 drops have been dispensed from the pipette, waste no want not

By reagent do you mean the CRS 1/40 calibration solution? I don't return any of that. I've made fresh a couple of times and just made another litre today as I'm about to start a new pot of CRS, I tested today and got the higher reading of 243mg/l caco3, I'd been using 214mg/l caco3

So to leave a residue of 30 would mean an addition 1.2ml/l whilst I've been using 0.9ml/l so that would lower the pH even more Oh, I brewed yesterday and got the low pH so 24hrs in between.

[Scooby]

Ok I'm in the middle of an experiment. I've checked the scales and cleaned and dried everything then tested the water 3 times, cleaning and drying in between, the average alkalinity was 238mg/caco3.

I measured 4l of water and treated for a target residue of 27mg/l caco3, on testing after 10mins the residue was 34.2mg/l caco3. In such a small amount of water I decided to go with that.

I poured 1l into a pan and calculated how much untreated water I needed to add to the remaining water for a target of 60mg/l caco3, after adding the resultant water and testing again it was just short at 54mg/l caco3.

I repeated the above with a target of 120mg/l caco3 the result is 126mg/l caco3

So I have 3 pans with with a litre each of 34.2, 54 and 120mg/l caco3, I'm off to walk Castro and clear my head of all the figures, then the oven will set to 65c and we'll see what happens.

[Scooby]

Talk about muddying the water

34.2mg/l caco3.....pH 4.7
54mg/l caco3........pH 5.0 just
120mg/l caco3......pH 5.0
Strip put under the tap......pH 7+

At least I've got some more wort to bottle I'm at a bit of a loss at the moment as my beers haven't been noticeably different in there fermentation or taste. I think I'll boil the night before and rack on the day next brew and see what gives, and get some more pH strips or pull out that old tub of pH 5.3

[Scooby]

Hadn't thought of that, less hassle than boiling

When doing that should I use the supply water as is or treat with CRS to lower alkalinity to a prescribed level as I have been doing

Still annoying me that the experiment didn't go as expected and didn't give me any answers

[Scooby]

I got myself some Aqua pura today and thought I'd repeat the test I did mashing with my supply water. I checked the alkalinity of the Aqua pura just to satisfy myself that the procedure, CRS calibration solution measurements etc were correct, I made it 22mg/l caco3 so close enough to the 20 you said Chris

I mashed a small quantity as before and dipped it after 10 mins with this result;



22 (20)mg/l caco3 pH 5.0 Aqua Pura

34.2mg/l caco3.....pH 4.7
54mg/l caco3........pH 5.0 just
120mg/l caco3......pH 5.0

The fact is all the tests have Iv'e done have struggled to reach 5.0 and nowhere near 5.3pH so the pigeons are filling their crops with corn and I should have some new strips by Friday

[Scooby]

I reckon there must be a shelf life on the strips, as I said they're about 2 1/2 yrs old and have been giving me consistent results up to about 6 or so brews ago when they seemed to be drifting down.

In the photo the light is reflecting on the dampness of the strip and I admit it looks closer to 4.7. In daylight at the right angle it's closer to 5.0 but as you said still points to the strips miss reading, anyway they've been chucked.

After my success inoculating the white lab slants from CPD I'm going to have a go at making my own. I have some agar and will make them up tomorrow. Along with the strips I've a couple more yeasts winging there way here so when I get the starters going I'll have some additions to my collection

BTW I bought 6 x 5l Aqua Pura at £1.32 bogof, I put one on the conveyor along with 3 or 4 beers and mentioned to the cashier that I had 6 and pointed at the other 5 in the trolley, I didn't realise 'till I got home she only charged me for one. That means I'll have to do a 30m round trip tomorrow to pay my dues