Just got myself a pressurised Rover 25 expansion tank from Autobreakers (only 2 days by RoyailMail!!) and it came full of crud from its previous
incarnation. After trying washing-up liquid, white spirit and vinegar (separately) with no joy, my wife offered me her magic balls (oo-er, missus...
is what I said to her!).
5 minutes or so of shaking later and the tank was clean as a whistle.
Looks like the balls are copper, or copper-covered iron, since there were lots of copper flakes after the cleaning and quite a few of them had gone
dark.
You can get them for about £3.99 from Lakeland Ltd. (apparently a place where you can get things for kitchens, cleaning, etc. - I wouldn't know
anything about those 
)
Rescued attachment 2005-08-21 4 Locost Magic Balls.JPG
Those are big balls you have there!
I took away my favorites, maximized the window and they still wouldnt fit on the screen
Good idea thoug, I filled mine with grit,sand stones, bleach, weedkiller but it still would'nt come clean, so I bought an ally one from MNR 
[Edited on 26/8/05 by ReMan]
As they are re-usable, do you fancy hiring your balls out?
Pat...
Just used Washing detergent and Boiling Water - left overnight. Came up a treat!
I cleaned mine out before fitting it.
I'ts as bad again now
I used some of the small stone chips from the garden and just swirled them round in the bottle.
simple as that.
quote:
Originally posted by ewanspence
I used some of the small stone chips from the garden and just swirled them round in the bottle.
simple as that.