In article ,
newshound writes:
On 29/09/2017 17:29, Dan S. MacAbre wrote:
Does anyone here sort of 'make their own'?Â* I buy glacial acetic acid
off ebay, because the missus uses it (well diluted, of course) as fabric
conditioner, although it doesn't really condition it AFAICT, but she
seems to like it.Â* Anyway, it's not as good as I'd imagined at descaling
kettles, even though I thought it'd be stronger.Â* I think the bought
stuff contains citric acid, but I don't want to buy a load of ebay just
to have it sit on the shelf for the rest of my life next to the Bradex
Easy-Start.

Fernox DS3 (sulphamic acid) is not cheap, £16 for 2 kg, but makes up a
large quantity, and is said to have an indicator (so it can be re-used
until exhausted). I've just bought some for a business, but they are
still on their first batch which hasn't run out yet.

I use Furnox DS3.

The 2kg tub would probably last a lifetime descaling your kettle.
(I believe they do a smaller pack too, but it's poor value for money.)
I use it for descaling plumbing fittings too, and I think a tub
lasts me 10 years. Usually buy from BES - I've actually bought
loads because other people keep asking me for it. There are
4 x 2kg tubs in a box, if you want a convenient boxed quantity.

It has an indicator dye which turns from yellow to blue/green IIRC
when the descaler is exhausted. Only time I descaled something that
required multiple doses was a secondary heat exchanger in a combi,
which had blocked with scale. It also has a smell added, so you
can quickly spot if someone tries to make a cup of tea/coffee
when you were halfway through descaling the kettle. (The other
give-away is the milk curdles instantly when you pour it in if
there's even a tiny amount of sulphamic acid left.) Beware of
the fumes - scale fizzes vigourously, and the resulting fine
spray given off from the liquid surface takes the inside off
your nose if you accidentally catch a whiff of it.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]