On Mon, 19 Aug 2013 01:30:26 GMT, Windmill wrote:

It ought to be in the small print of ingredients as g/l.

Hard to locate, though, and then you have to decide if 6 sachets
containing 7g/l., to be diluted with X litres of water and allegedly
capable of treating 50 sq. metres and costing 9.99 is better than 20
sachets ... or .... and so on.

No different to grocery shopping. Never assume an "offer" is the best
value, around 50% of the time it is not.

--
Cheers
Dave.