pH - how low is too low?

[Blackaddler]

I'm just treating the water for a brew tomorrow. A very pale beer, with 33% smoked malt, ~5% each Caramalt and Tor. Wheat.

This is the second time I've used my pH meter, and it calibrated OK [ie. didn't need any adjustment].

With 86L in the HLT, the water measured pH 7.56. I've added 99ml AMS [CRS] as per Jim's calculator, and the pH is now 3.23!

Is that too low? Should I bring it back up again? If so, what's the best way?

I also plan to add about 4gms of Calcium Chloride to the mash and/or boil.

[WallyBrew]

3.23 is too low. If you had removed all the alkalinity the pH should be 4.5 so you've overdone it.

Start by taking about 10% of the water out and adding back the same volume of untreated.

[Blackaddler]

I was thinking along those lines. What's the minimum pH that I should aim for?

Edit: I had to take out quite a bit more than 10%. Somewhere between 25-30L.

After a bit of adding some back as well, etc, it 's now pH 5.5.

[WallyBrew]

I'll pass on that as pH isn't really a measure of the buffering power of the water but at 4.5 you have no alkalinity left. I'd guess that you probably want about 50 of alkalinity for that mash so perhaps you should remove 25% of the water. You probably already have about 100 of calcium in your water which is sufficient for the mash.

Re: the calcium chloride I was told by my old boss who was a consultant to quite a few breweries that you do not put chlorides through the mash tun but unfortunately I have forgotten why.

Edit: having just posted this I see that you have just done the above

[Blackaddler]

IIRC, not all the calcium or chloride gets carried through to the boil.

I usually split any CaCl2 additions, 75% in the mash and 25% in the boil, to make sure some gets through. With this small amount, I shall probably add it all to the boil.

[mabrungard]

I don't expect that Jim's calculator is that far wrong, so is it possible that your actual water alkalinity is lower than you input to the calculator. Did you check the tap water alkalinity with a test kit? A water pH of less than 5 is likely to be too low. There is a water acidification calculator in the Bru'n Water software that can provide a second check on your acid addition amount.

[Blackaddler]

I don't have an alkalinity test kit, Just a pH meter. This is the second brew I've used it with. The first brew [at the end of October] was a strong dark beer, which required 57ml AMS.

Tap water pH 7.48,
HLT pH 7.63.
After 57ml AMS addition pH 6.06.
Mash pH 5.36.
Post boil pH 4.75

All in the right area, and produced an excellent beer.

So, back to this brew today..
Tap water pH 7.40
HLT pH 7.56
After 99ml AMS addition pH 3.23. Adjusted pH by removing liquor and adding more tap water... pH5.50 [@ 8°C].
Later on, I thought I'd recheck a sample of the liquor after warming it up to nearer room temperature... pH 5.69 [@ 24°C].
Mash pH 5.45
Post boil pH 5.41

I'm still getting used to using the pH meter, but I'm just wondering if CaCO3 levels [normally ~265mg/l] have been reduced. The local reservoirs have probably been topped up with the copious amounts of rain we've had around here recently.

[Eric]

1ml of CRS can neutralise 183mg of CaCO3.
99ml will therefore neutralise 18117mg.
That could be 211mg of CaCO3 in each of 86 litres of water.
If it was intended for the remaining alkalinity to 50ppm, then it would have been thought that the initial alkalinity was 261mg of CaCO3 per litre.

If 27.5 litres were removed from an evenly mixed liquor of 86 litres containing 99ml CRS, 58.5 litres would remain with 67.3ml CRS.
67.3 ml CRS can neutralise 12316mg CaCO3.
With that liquor topped with water to 86l, that reduction could be 143mg/l.
If it was assumed that the liquor was at that point marginally alkaline, the initial alkalinity of the supply might be assumed to have been in the order of 150mg/l CaCO3.

[Eric]

1ml of CRS can neutralise 183mg of CaCO3.
99ml will therefore neutralise 18117mg.
That could be 211mg of CaCO3 in each of 86 litres of water.
If it was intended for the remaining alkalinity to 50ppm, then it would have been thought that the initial alkalinity was 261mg of CaCO3 per litre.

If 27.5 litres were removed from an evenly mixed liquor of 86 litres containing 99ml CRS, 58.5 litres would remain with 67.3ml CRS.
67.3 ml CRS can neutralise 12316mg CaCO3.
With that liquor topped with water to 86l, that reduction could be 143mg/l.
If it was assumed that the liquor was at that point marginally alkaline, the initial alkalinity of the supply might be assumed to have been in the order of 150mg/l CaCO3.

This suggests for 50ppm to remain you would need to reduce alkalinity by 100ppm needing 47ml CRS in 86l.

[Blackaddler]

That makes sense... although 150mg/l CaCO3 does seem very low for this area.

I might check with some local micros, to see if they've noticed a big difference recently.

[WallyBrew]

If you are happy with your pH meter and do not want to buy an alkalinity test kit follow this method. The end point is when your pH is 4.5.

[Blackaddler]

Hmm... Methyl orange... sounds like a defoliant...