Could it be pollen from plants in the fields or trees? You could try buying a skimmer which would clear the pond surface of any floating debris. It attaches to your pump and very quickly cleans the surface and keeps it clean.

hi, perhaps it is tree pollen. Many of the larger trees and i see you have a good selection, use wind pollination.
other then collecting a sample and sending it for analysis I can only suggest that.

is there the same dust everywhere as in its come down in the rain? just another thought.

Tree pollen is very common at this time of year. Working as an environmental regulator I soon got used to complaints of 'oil pollution' on roadside puddles after rain. This always tutned out to be pine pollen. It won't do any harm and the wind will soon blow it to the side of the pond.

What a lovely pond and garden you have, very charming.

Does the film dissipate during rain or if you hose it? If so then it is likely to be pollen. My uncle's pond gets it as it is surrounded by woodland. Perhaps it is also the heavier rains than normal are washing fertilisers into the pond, which may be the case if your home is surrounded by working fields.

Thanks everyone , I think it must be the tree pollen , we have not had any decent rain so I guess it has blown from the wood to us , hopefully it will disperse with a good downpour.

it looks healthy enough id guess the same as its getting caught in the waters serfice tension ie the skin . even if its as said pollen it could stop the oxygen getting in so well . thats what a protien skimmer does in a marine tank . oxygen only comes in threw the surfice of water . if you get any fish up gasping id buy a nice pump with a fountain . put it on some blocks in the middle . (i hope you got some waders lol) this will push all that stuff to the edge and buy cassing waves or ripples excuse the spelling will double or tripple the surface area . if it seams fine thow dont worry . ps im very envious of your lovley big pond . a gunnera there somewear would look awsome .

have no idea what it is BUT I have to say that I think your pond is beautiful and I love the island and the building on it :-))

You might have some fun demonstrating surface tension before you get rid of it. Put a little washing up liquid on the end of your finger and touch it to the surface of the water. All the pollen or dust or whatever will spread out away from it! I actually used this method to collect the duckweed on our very small pond as you could make it scoot off all to the same place where it was easy to scoop out! A tiny drop of liquid won't hurt at all, but use eco friendly if it worries you.

washing up liquid takes all the oxygen out of the pond so i wouldnt .sorry steradram x .