We love our big koi pond with the bio-filter that keeps it clean and all the lilies, both the big night blooming red ones, and the various color day blooming lilies (one of which has an amazing perfume). We also have some lotus plants but the koi trim them back too much lately for them to bloom. The koi mostly eat algae on the bottom of the pond. You can see them see-sawing back and forth when they rip pieces of algae off. But they prefer the food I throw in occasionally (and the tasty lotus roots) and the video below shows them swimming around happily eating.
Our pond has a plastic liner that is rated for thirty years but we have some doubts about those years, perhaps they are only in dog-years. So we are thinking about replacing the plastic liner with pool cement soon. If the liner was replaced we could also offer our pond for guests who would like to swim in a natural pond without hiking for twenty minutes to our rainforest pool above a waterfall. Below you can see a picture of our nearby waterfall.
We have been thinking about making our koi pond into a natural pool that our guests can also swim in without first hiking through the jungle (on an amazing nature trail) for twenty minutes. The first step to that process will be building another koi pond back under the jungle suite so we will have a place for our beloved koi and the many varieties of lilies and lotus plants while we drain the big koi pond and line it with pool cement. The new pool would use the existing bio-filter and some more plantings on the side to keep the water pure. We probably won't be able to return the koi as they are very large and we don't know if our guests will be comfortable swimming with them.
When we start the new pond I'll put some pictures and drawings in another blog. It will have a bio-filter and waterfall too but we might also include a UV sterilizer (to clump up the algae) as a test to see how much clearer the water is.