I suggest you try barely straw bundals you can buy it either ready bundled to suit the size of pond or in mini bales that you can stuff into tights or similar and anchor to the side of the pond. This will help but really you need a lot of plants to take up nutrients and create shade on the surface blocking light getting to the algae. Lillies work well for later in the year (they are only just shooting) but at this time marginals casting shade help
The pond is around 4 x 2 meters, and 2 foot deep at the bottom end, raising to nothing at the other.
I have loads of pond weed, good airator, another similar plant that usually grows and sits elongated on the surface (not sure of the name) and a pigmi lilly. Of course all of these were cut back and small at the moment.
I think the major problem is the sun light, it gets the early morning and mid day sun.
I've tried barley treatment and barley bails, they do nothing. I'm currently trying another bio treatment, but I have a horrible feeling the pond is just in the wrong place, and I'm not built for digging!!