You are looking to create a patio pond. I have one that has goldfish, a few plants and a small air stone. It's lovely. No water conditioner needed if you fill it and let it sit for 24 hours before adding fish. The chlorine will dissipate. But please - no koi! They get very large very fast - a 4 inch koi could grow to a foot long koi in one season.

I have a 50 gallon in ground mini pond by the front door and it is a great spot for relaxing. It has plants, 1 goldfish and a fountain pump. If you are using city water and they use chloramines they will not dissipate so you will need to use a de-chlorinater. I second the 'no' koi, they grow too big. A Shubunkin is a calico goldfish and very hardy. Goldfish tame easily to come eat. Toads and/or frogs will move in and lay eggs so soon you will have tadpoles.

You can put a mini waterlily, a couple of water hyacinth (they mass produce quickly so you will be composting them soon but they are worth it), mini papyrus works great in a patio pond too. That way you will have something tall, medium and floating. 2 things that flower. It needs to be in a spot that doesn't get too much sun or the water will get too hot.

I have 3 big pots that have lotus in them and they are in sunny locations so they don't have fish in them. I tried fish a few years ago but the water gets too hot and they died :c( so no more fish in these pots. The tree frogs have laid eggs so they are full of tadpoles. They don't seem to mind the hot water.

Good luck with your mini pond.

Ah you are correct! City water MAY have chloramines - ours does not, so I forget about that!

I have a number of ponds but also an earthenware urn that I coated to ensure it was waterproof. The only plants in it are Water Lettuce (Pistia stratiotes) and a small Lotus (Nelumbo nucifera). When the Lotus gets bigger I'll remove it. The Water Lettuce multiplies and its hanging roots clean the water. When I take out the excess plants that is effectively removing excess nutrients. There's no filter and the water gets topped up by the garden sprinkler system. There are some small fish to clean up any mosquito larvae, Checkered Rainbow Fish. It works quite well but I do have to occasionally add some food for the fish. It does get overhead sun but I've got it sheltered from angled sun hitting the sides. The plants stop the overhead sun from overheating the water. I have my own water supply so no problems with chemical additives.