Unfortunately, all trees shed leaves, even conifers, although their leaves are needles. Evergreens do it year round, deciduous ones all at once in autumn, but either way, they will drop stuff into and around your pool. That being the case, you might be better off choosing a deciduous tree instead - at least you know when its leaves are coming down and can get prepared in time by covering the pool, and you presumably don't use the pool in winter, so the bare branches won't be a problem from a privacy point of view.

Hello Sylvia and Norman. I'm sorry, but I can't think of any living plant that will not drop leaves and / or other bits and pieces into your pool.

Even if you used deciduous trees as Bamboo suggests, they will drop bud scales in spring, dead flower remains and surplus seeds before the autumn influx of dead leaves.

I don't think there is a trouble-free solution for you. How about applying for planning permission to raise the wall a couple of feet? Or add some netting to partially block the view?

Idea! How about some silk flags on flag poles inside your garden? You could have some of those tall, fairly narrow ones that have been "in" for a while - like these -
http://tlcsigns.co.uk/extendable-flagpoles-for-portable-use/

You could make your own flags if you have any ability to sew.

Mine is almost the same as Beattie, last week I saw sails draped across a patio to give privacy from above, the open front Arabian tent idea might work

I've seen "sails" used over a pub patio to give shade from the sun and to give smokers shelter from the rain. I guess they could be used vertically, or at an angle to stop "peepers".

The pones are saw were at an angle

Eh? What?

I'd guess that should read 'the ones I saw...'

Thats right lol

you cant have a taller wall but you are aloud as tall a trellis as you want which you could grow evergreen climbers on thow as bamboo etc sais all plants shed leaves just some more than others . you could havea lovley pagoda overat least some of your pond . theres a way of angling the wood on top like a louvre door so from a perticuler angle you can not see in the pond but it lets light threw from all the other angles . ive seen this in the local garden centre .