Hi

Sounds intresting, if me I would make a bog garden and have a watercourse separate if you want a waterfall effect as I can imagine all the compost/ soil getting washed down to the pond and causing problems

and making the waterfall separate would be easier, but it could still look like its coming out of the same area

Don't do this. It will make the pond water continually muddy. Instead have the pump feed into a filter pond at the top. They sell preformed ones with a spillway. Make sure the run back to the main pond has lining underneath of it so you won't loose water. With the filter pond you won't need a pressure filter at all. I have this arrangement set up for two of my ponds. Please view my blogs and photos. As for a bog area, dig out a hole of shape and depth that you wish and place the liner to cover the bottom then place in your soil and keep moist, there is your bog. Again, don't make the bog a contiguous part of your pond. Be patient, plan well and go slow creating this arrangement. Have it all in place but I suggest a full startup next spring. My view of these costly pressure filters is that they are totally unnecessary in an outdoor pond. If you are a novice to garden ponds now is the time to start informing yourself about biofilms and pond ecosystems together with the changes a pond goes through during the yearly cycle.

Thanks for the feedback. The thing is that the whole watercourse is already built the way I have described. However the original idea was to have the top pond as additional filtration which I may go back to following your comments. I had in mind reeds originally but the depth is I think too shallow for these. What I cannot do is tear it all up and start again, but I can modify my ideas. We have tested thwe watercourse with the exception of the pressure filter system, and it need just a little tweeking to work well. It is incredibley soothing to have running.

Has anyone any advice about what to have in a filter pond? The basic shape is there and the liner is in. I have water feeding in at one side tumbling down a few rocks. At the far corner there is a spillway into the water staircase, that feeds into the pond at the bottom.
Since putting loan into this filter pond is a bad idea, how do I grow and filtration plants?
Secondly what plants should I be looking at growing?
Thanks,
John