It sounds like a 'wildlife pond', if you google you'll find loads of advice on how to maintain it (mainly 'do nothing' - my kind of pond). They are fantastic and support so much life. Sounds good that the water is clear, and plants round the edge to allow safe access in/out for wildlife. Also great that it is fed by water barrel. Need a decent amount of surface plant coverage to keep sunlight out and keep algae down in spring. I wouldn't put fish in or it gets a bit more complicated. If you get more plants choose native ones. Garden centre should advise on those but beware because they DO sell some invasive species that will take over your pond and are a threat to the environment. Enjoy your pond, I'm jealous, we moved to London and now have a postage stamp out back.
We have recently moved into a house that has a good sized pond. It's really healthy - it's full of frogspawn we've seen a frog and a newt this week already. I am terrified I am going to somehow kill it. It has a few different plants (no idea what any of them are), a few wee blobs of algae and loads and loads of those reedy things around the edges. The water is pretty clear - you can see down about a foot into the pond. It's fed by the rain barrel to keep the water level topped up, and the whole area around the edge is pretty boggy - the previous owners had the whole garden quite wild.
Will it pretty much look after itself or do I need to do anything? Skim off bits of leaves from the surface? Keep an eye on the plants to stop it getting overgrown? Anything else I don't know about?