A while back I posted about how best to go about filling the pond in the back garden in and I've made some progress.

This weekend I want to get it finished and have lined up a couple of mates to help out.

I was trying to work out how much sand/cement I'll need to finish the job off and it seems like an awful lot.

I've put down some hardcore, but need to put down some more as one bag wasn't enough. I am planning on hiring a whacker plate to flatten that off and then use about an inch of sand/cement wet mix (web seems to suggest a 6:1 ratio) and then lay the slabs on top of that.

The area is about 9.4m^2 and so an inch deep would give me a volume of 0.235m^3 (9.4*0.025) From what I have seen online this will require about 20 bags of the 25kg pre-mixed concrete. I was looking at the pre-mix stuff for ease of calculating, but will probably buy the sand/cement and mix it myself.

If 20 bags is about right, then I supopse i'll need 3 bags of cement to 18 bags of sharp sand for a 6:1 ratio.

I don't really want to end up with loads of left-over bags that I have to get rid of and equally I don't want to keep having to go back to the builders merchants to buy more while doing the job.

I keep imagining 20 bags of this stuff and it seems like an awful lot for just an inch thick layer. Does this sound about right? All help gratefully received!