Simma is spot on.
So you're aware your Coopers stuff uses an active ingredient called 'Sodium Percarbonate'.
This is exactly the same active ingredient in Napisan, Homebrand Napisan, and the sachet percarb that Brewcraft and others sell in their stores. As a result most of us tight-arsed brewers don't buy the brand name product like the Coopers - it's much cheaper to get a Napisan or Homebrand Napisan at the Supermarket. Plus the concerntration of Sodium Percarb in Napisan/Homebrand Napisan is much greater so not only are you getting a cheaper deal you're also getting a more effective cleaner.
The Coopers stuff and the other products I've mentioned above are all effective
cleaners, but won't
sanitise thoroughly. That's why many people here recommend using Starsan, bleach and other products in addition to cleaning with something like a Coopers. The term 'Sanitiser' on the Coopers product is somewhat misleading and some would argue shouldn't be there. If time and funds are an issue, I would recommend even using boiling hot water on your gear from your tea kettle to help knock out the bugs in your gear after using the Coopers product, as the Coopers product alone, particularly with just warm water will not do the whole job. I have mates that have used this Coopers Sanitiser and stupidly use cold water and do get regular infections.
You will find all the correct info on the subject here, John Palmer's book 'How to Brew' can be read in full online, but I keep purchased book version handy to refer to:
What 'cleans' vs 'what sanitises' - John Palmer How to Brew
Cheers and all the best with it,
Hopper.