Doesn't that combination give off a very potent and poisonous gas??? Careful!! Don't become a Bangkok Post headliner!!

I think you're thinking about ammonia and bleach. That makes chlorine gas - one of the poison gases used in WWI. Caustic Soda and hydrochloric acid just make salt and water. But if they're both concentrated it can do it with a lot of heat and give you some blow back from the pipe.

Papaguido, thanks for the offer, however I'm in Phuket currently, which is where the problem is.

I tried to get a long rod thing today from a major plumbing and electrical shop, but all they could offer me were long metal things for pulling through electric wires, which after one chap tried to sell to me, another then told me that it was no good for that purpose.