I have been changing some of my air stones through the summer as they have slowly become blocked, left them on the shelf for a while, I thought as I have no acid which would probably open them up I'd try giving them a light rub over with my grinder

this was before the grinder (click on it)
[url=http://s107.photobucket.com/albums/m302/wet ... before.flv][img]http://i107.photobucket.com/albums/m302/wet ... before.jpg[/img][/url]
This was after
[url=http://s107.photobucket.com/albums/m302/wet ... 1after.flv][img]http://i107.photobucket.com/albums/m302/wet ... 1after.jpg[/img][/url]
before
[url=http://s107.photobucket.com/albums/m302/wet ... before.flv][img]http://i107.photobucket.com/albums/m302/wet ... before.jpg[/img][/url]
after
[url=http://s107.photobucket.com/albums/m302/wet ... 5after.flv][img]http://i107.photobucket.com/albums/m302/wet ... 5after.jpg[/img][/url]
Ok so its the wrong end of the summer but the filters are boiling again.
[url=http://s107.photobucket.com/albums/m302/wet ... 010247.flv][img]http://i107.photobucket.com/albums/m302/wet ... 010247.jpg[/img][/url]
[img]http://i107.photobucket.com/albums/m302/wet ... 010237.jpg[/img]