I'm still working on getting good chain tension and just spent some time searching through the old posts that related to this. In the drop down box on one of them that I came across all it says is 'you can try wedging a granny...' Now that made me laugh! How wedging someone's granny has anything to do with chain tension I'll never know!
(of course the more complete version is: 'You can try wedging a granny gear 'tween the upper and lower portions of the chain..')
(of course the more complete version is: 'You can try wedging a granny gear 'tween the upper and lower portions of the chain..')