You could get a patio pond from Aquascape. I have one, and it’s great! https://momhomeguide.com/my-new-patio-pond-a-patio-pond-giveaway/
Stella, here are some ideas. Hope this helps:
You might want to start with a preformed plastic pond. Dig a hole for it to fit and place it in. Make sure it's level. Get the best pump you can afford. Buy water plants to keep it clean and prevent algae.
We have had a pond for over 30 years. We dig our own. Have done this twice in 30 years. Determine how deep it needs to be. If you will have Koi - it should have a spot at least 24-36'' deep - depending on where you live. We just laid out an old garden hose in the shape we wanted - we chose a kidney shape - approx 5 x 8 feet. We dug it out (hubby did the digging) and he left a shelf around the widest part to sit planting containers for water lilies, etc. We then purchased a heavy pond liner and then laid large stones around the edge to hold in place.
We used a double layer of heavy black plastic on our first pond - think ECONOMY. But it lasted several years.
We have had Koi for years and years, but in just the last 3 years something has managed to get into our pond during the winter (even though it was covered with screening and netting) and feasted on our Koi. We lost NINE 14-16'' Koi 2 winter's ago, seven 6-8'' Koi last winter. We have 5 more this year and will try a 'tighter covering' this winter and HOPE. Pretty sure it was racoons. :0(
The first year we did not use a filter or a pond pump and our water was crystal clear. We had pond lilies and plants and koi. Must have had a good balance. We now have had a home made bio filter (check out Skippie's online) for several years that keeps the water crystal clear with ZERO maintenance. and a nice waterfall pump. You can go either way. Depending on budget.
Wishing you success!
Backyard pond with Skippies bio filter and Koi.
Here is the link to Skippy's pond page. LOTS of good info and stuff here. We love our bio filter. We used a 70 gallon Rubbermaid container and a bunch of 'scrubbies' we purchased from Skippy's site. Best thing we ever did! Saves so much work!!!