thanks for the replies guys. Miya - no pics yet, this is all theory still.
i have an initial plan, but it will probably change once i get the scalled mock drawn. but basically the java moss will be in the 2 sump areas. and they are great at balancing nitrites and nitrates. and are not leafy so they dont give off too much big floaty leaves.. the water from this area will flow through the bio filter so the debris that gets through will add to the natural cycle and in theory keep the algae/bacteria/ph balanced.
Nardus - the reason i plan to put these in the sump areas and not in the pond is so that i can easily maintain without having to enter the pond. i am hoping the only maintainance would be to trim the moss from over growing. lol.
thanks. as soon as i have a definite plan i will post it for all to see.. and 1 point i have to make is that this is nowhere near to msot of your ponds. its only a 4000l. so its a tiny little display that will be in my tiny little garden.