hello there Baz, hope things are going well...I TOLD you to be patient!!
As I mentioned, you
may need a booster pump...type booster pump into search and see what comes up...from what I`ve read, you should expect about 5/600 litres a day...(I gather that means 24 hours)
Putting your tap water through the pump, as you are now doing, should help though.
Andrew McCann uses a 200 gallon a day system...he may be able to help.