Hi mimififi,
I think you will have endless hours of interest and fascination with your new wild life pond, I have a couple myself, one for fish and the other just for amphibians etc.
I also encountered the "pea soup" problem at first but now I've seem to achieved my ultimate aim and reached a natural balance, what I did to speed up this process was crumble up 1 or 2 handfuls of earth (clay soil is best) and cloud the water with your hands as you untill its murky, this will block out sunlight and also sink algae to the bottom as the fine particles settle.
Wow thats pretty deep for a small pond! I have a small solar pump in mine, which I picked up for a tenner, it just floats on the surfice and sends up a jet about 12"-16" high, but only in good sunlight. it has 4 differant fountain heads which occaisionally need cleaning. My golden rudd seem to enjoy the fountain.
I did try barley straw but found tadpoles munched through blanket weed quicker than anything! For surfice shading, I found the 'water fringe' ideal for a small pond, 3" max leaf size with yellow flowers and its native too.
Good Luck. T bird+