On 12 Jun 2005 19:04:54 GMT, mike ring
wrote:

Sorry the subject lines a bit cryptic, but I'd like the brains truss to
tell me what's going on here.

My plastic water bottle, which is refilled regularly with tap water, was
suffering a bit od green algae, so I put some of the above crystals in, and
a bout 1/3 filled with hot tap water, put the cap on and gavre it a shake,
and it foamed up like Andrews.

I expected a pressure buildup, and was ready to ease the cap, but the
opposite happened, and the bottle was squashed nearly flat by air pressure,
and developed a permanent dimple in the bottom, so some serious vacuum was
being formed.

But how? - it's alleged to have 15-30% oxygen based bleaching agent, and
5% non-ionic surfactants, 5% anionic surfactants,(whatever all those are)

It does a good job on the algae.

I'm not too sure about the variations of Cillit Bang, but I have a
bottle of CB Universal Degreaser, which despite it's silly name does
seem to work (on the inch-thick-of-grease leccy hob) . However, there
is a caveat on this particular variation that it isn't suitable for
direct food contact surfaces, which I assume to include the insides of
water bottles.

Perhaps the crystalline stuff IS suitable for food-contact surfaces,
but it is worth checking out.

Regarding the contraction effect, I'm no chemist (it's the subject I
failed at O level!), but perhaps the hot water was cooled quickly by
the CB thereby producing a partial vacuum. Have you tried reinstating
the plastic bottle by pouring in hot water and leaving the cap off
until the water cools?

--
Frank Erskine