Aerated water for brew

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No, not that kind of brew. A cup of tea......

As we live in a relatively soft water area we've never suffered from the dreaded tea scum.
We've recently had a new kitchen sink tap fitted and it has one of those aerater things on it and we now get tea scum 😕 I know they can change the ph of the water but is it enough to cause our brews to form a tea scum? As a test I removed the nozzle thingy for my morning brew and, lo and behold no scum. Surely something as simple as an aerator on the tap can't cause the dreaded scum?
Thoughts anyone......

Cheers Tom
 
That's fascinating. I've not thought about tea scum much (my wife's the tea drinker, not me). But I'd always thought it was due to hard water. It'll be good if someone with a good grasp of chemistry can explain it

Good scienceing!
 
Ah, from a quick Google, I've got a possible explanation.

https://www.quora.com/Does-aeration-affect-pH

Water out of the tap contains a small amount of dissolved CO2 which lowers the pH. The aerator drives this off, so the water pH rises.

The scum is a result from the bicarb in the water reacting with the tea. People say adding a bit of acid (lemon juice) can prevent this. The slightly lower pH from the CO2 may have the same effect.

But then I'd also expect the CO2 to be driven off and the pH to raise when the water is boiled. Ok, that's my theory down the drain...

Back to square one
 
As far as I know scum is all about the carbonates. We have to take a water filter away on holiday so we can make a decent brew as the bottled water in Greece usually has quite a high mineral content.
Maybe the aeration of tap water changes the ph enough to have an effect on the mineral composition. It's alchemy I tell you

Cheers Tom
 
Ah, from a quick Google, I've got a possible explanation.

https://www.quora.com/Does-aeration-affect-pH

Water out of the tap contains a small amount of dissolved CO2 which lowers the pH. The aerator drives this off, so the water pH rises.

The scum is a result from the bicarb in the water reacting with the tea. People say adding a bit of acid (lemon juice) can prevent this. The slightly lower pH from the CO2 may have the same effect.

But then I'd also expect the CO2 to be driven off and the pH to raise when the water is boiled. Ok, that's my theory down the drain...

Back to square one
I did read a very similar report.
If removing the little filter does the job then I'll be happy but I'm more curious now as to the actual reason when the only change is the new tap/aerator

Cheers Tom
 
Throw a bit of AMS in it 😁

@soupdragon what's the address of local shop or something. I would like to see the water report.

I did some experiments last year with our own teabags making completely different cuppa on holiday. Cornish soft water made bright orange tasty tea when it's normally grey and scummy.

I agree it's bicarbonates... But there had got to be a bit more to it...
 
Throw a bit of AMS in it 😁

@soupdragon what's the address of local shop or something. I would like to see the water report.

I did some experiments last year with our own teabags making completely different cuppa on holiday. Cornish soft water made bright orange tasty tea when it's normally grey and scummy.

I agree it's bicarbonates... But there had got to be a bit more to it...
Local Tesco store. Water is supplied by united utilities

Wallasey Liscard Express
15-17 Liscard Village
CH45 4JG

Cheers Tom
 
That makes interesting reading.

@peebee what does the defuddler make of that. Can it cope with tea?
...
Grr, the "Defuddler doesn't work with tea or brewing water for that matter. It works with the water reports to make them comprehensible ... whether or not you then go on to make tea or beer with the water.

@soupdragon

Do you drink you tea Black or with milk?

That's more like it! I'd struggle to see how CO2 could create enough scum to be visible in soft water, but if it interacts with the precipitate tannins form from adding milk (tannin in tea precipitates casein out of milk - remember that from school making the earliest "plastic" of casein-formaldehyde). CO2 is best known for creating Carbonic Acid in water, pH drops, but it doesn't stay like that long (unless pH drops a lot). The crazy "carbonate" chemistry sees it change to bicarbonate, so the pH goes up like @Agentgonzo was saying. I don't know much 'bout chemistry, but me imagination ain't bad.

I used to get scum on my tea out the "Tea Maid" (loads of mixing in air) that tried to wake me up at 4am for me milk-round. The Derby water was "medium soft" and never formed scum in tea using the kettle.

Funny, that was a conundrum in my early days, and I haven't had to think about it again 'til now. Told you me imagination is good! (Ever since I got that almighty bang on the head ... 🤪 ).
 
Without the aerator fitted inside the spout the water will still "swirl around" due to the presence of a strangely shaped thing that looks like the head of a thistle but with holes/channels through it. The resulting brew still has a small amount of scum but not the large coating with it fitted. Without the swirly bit installed the brew is totally back to normal and scum free.
Much oddness........

Cheers Tom
 
It's seems there are two types of film (scum) of tea.

Black tea have a thinner one that is air, carbonate and tea*

Milked tea scum is a heady mix including milk fat, carbonate, tannin and polyphenols from the black tea*

Both unsightly, but not harmful. Who knew...

*sources: Google. Various.
 
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