Thanks, billybobbs! Not sure what size to go for now! I think I'll go for 1kg of Syrian with apple and 1kg of Dwarf basic with flaked peas, to see how they get on with it.
Pompompoms is looking after them when I go on holiday in a few weeks time, so I shall have to start the change over as soon as I receive it so Pom can keep it going whilst I am away. Sorry Pom!
I throw so much of their food away, at least this won't go to waste. Cheers Silver!