Looks like I'm going to have to try sulphuric acid drain clearer on a nasty and difficult to reach drain blockage.
My friendly chemical supplier has 4 x 3kg doses for 15quid which is fine value wise but I'd rather not have 9kg of 93% acid lying around in the spares.
Any idea what the going rate is in the average plumbers' merchant and the typical size? I've found a few search results on the usual trade suspects' site but they're all a weeny 1 litre bottle and no prices without signing in.
Any ideas?