Looks great. Have you thought about adding fish?
I will only recommend Harlequin Rasboras and Neon or cardinal tetras.

Actually there is fishes in there. There is one Electric Yellow and Kuhli Loach that is living there for more than 4 years. The Electric Yellow eats the string algae and tiny ramshorn snail, I observed, as well as other unfortunate bugs that goes there.

In the background there is a cave-like shelter made out of 7 PVC pipes stack and glued on top of each other, and covered with pebbles for aesthetic, which then was covered with mosses and aquatic ferns.

I did try Neon Tetras and White Clouds in this tank, but they didn't thrive, perhaps because the lack of water circulation. Few weeks ago, I bought two juvenile Convict Cichlid.

Except for the Convict Cichlid, the fishes are very shy. I thought the Kuhli Loach was dead, but I saw a glimps of it once, a few months ago. When one of my dog was a pup, he used to stay in front of the tank and watch the Electric Yellow get close to the front glass and unsuccessfully pounce. He eventually stop, learning he can't catch it that way.

Sounds interesting adding the Convict Cichlids but i would think that they will succumb as they age. I just thought of another fish that should do much better:
Paradise Fish

White Clouds will not do well because your tank is much too warm for them. I have White Clouds outside (in coastal CA): in an old rectangular deep sink and in a Half barrel insert pool

I have ran an airline to the deep sink but the barrel insert is unaerated and in full sun while the sink is in full shade. The minnows do well and reproduce.
Another fish that might make it in your set up would be the American Flagfish, though it is herbaceous and will nibble on plants.
Surprised the Neons did not do well. May be due to pH conditions and overcrowding more than lack of water circulation.
The following article approachs the natural circulation of water in ponds. The same applies to tanks, especially if the surface to volume ratio is high. Natural cooling and circulation

I think most cichids are hardy fish, like the tilapia, however I read that Convict Cichlids prefer moving water. As of right now, one of the Convict Cichlid are very active, the other is in hiding because its being bullied by the other. It's fortunate that the tank has many hiding places.

The Paradise Fish is a great choice, but as of now I'm trying to stop myself from stocking more fishes. More fishes adds more bioload, and the balance of the tank might colapse. I hate scrubbing the algae of the glass, and I rarely do that now.

What plants have you planted in your Half-Barrel insert pool? I love to see a picture of that set-up!

I once placed a mosquitofish in the tank, I caught it from my local stream, but I have to get rid of it. They are just so ugly, in my opinion, and became aggressive. If people don't mind ugly fishes, then those fishes are excellent for these type of set-up.

The article of Natural Cooling and Circulation is fascinating! I want to believe that my tank naturally circulate water through evaporation or heating, but in reality, probably not. But I'm positively sure that the fishes does not lack of oxygen, not once did I see them gasping for air in the surface. I also see a lot of tiny bubbles after the end of the day trapped in the mosses and other plants, so I'm assuming that will provide plants with oxygen at night when plants consume oxygen and respire CO2.

Here are two images of the habitat.
I have about a 3 inch layer of river sand in the bottom of the tub with a large rock that sits just below the surface of the pool. I only planted Potamogeton in it as it is such a cool looking plant. I only recently added the water hyacinth but will probably have to remove them if they die over winter. I only can see the White Clouds at night when I shine a flashlight onto the surface as sometimes some will hang out near the surface. There are alot of snails in the tub. I am surprised that they do not bother the Potamogeton! I do feed the fish with Goldfish flakes but I am somewhat haphazard about the feeding!
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That's a great set up. I also planted Potamogeton and they are prolific plants in my experience.

I love mosses, and adding aquatic mosses to that setup is a must for me. If you acquired an aquatic moss, like the Christmas Moss that was a must years ago for every planted tank, it should thrive in that set up. They prefer cooler water and it's a great for the White Clouds, they will use it to spawning medium. Or you can just add the common Vesicularia dubyana, the Java Moss. Make sure it does not have string algae when you introduce it to your set up, though. I have it and it's not going away anytime soon.

What type of snails do you have in there? The ramshorn snail and the trumpet snail that I have don't attack the plants, or if they did it's very unnoticeable.

How often do you do water change? Or are you like me who refill the water loss through evaporation.

I'm glad I'm not the only one who has a tank/pond without using any electricity power.

I agree Randg. Glad to see someone else who enjoys a simpler way of ponding without all the hassle and costs of filters, pumps, etc. I have been ponding for years. My first were kiddie pools in which I had plants and fish. The best one I ever had was with American Flagfish that actually reproduced and thrived until I made the BIG MISTAKE of having TOO MANY PLANTS in the pool that simply filled in and choked out the fish. As my time was really tied up on work there was not much I could do. Just let it go. So now I focus on small pools with only one major plant in the pool and maybe one or 2 cover plants.
The only thing I have ever done with the pools is to irrigate by running tap water into them. Though now I will dip into the pools and remove whatever algae I see growing.
I consider the snails to be pests as they came in with the plants. They are just regular pond snails.
What I would love to do is to set up some ponds and grow some of the neat freshwater native fishes that are available but I am currently having problems with raccoons getting into the yard and making a mess. They have already destroyed one pool by breaking down the sidewalls and it is simply impossible for me to do much apart from removing as many of the smaller plants into buckets until I have the time to really tear down the old pond and set up a new one. Have been experimenting with a racoon repellent that seems to work. Has seemed to keep them out for the past 4 weeks. They even got into the tub above and tore up the Potamogeton but I just stuck the loose stems back into the sand. One reason I added the hyacinths so that I could more easily tell if the racoons return.
Your comment of not using electricity is interesting as I ran across a natural way of aerating a still pool by using wind power! Windmill pond aeration system

The systems being advertised are way too huge for small pools but maybe someone could rig up a smaller windmill and have a tubing set up that feeds several small pools??
Just made some images of a pool in the ground with a Sagittaria species as the dominant in pool plant and with Rosie Minnows. It is out in my front yard jungle and gets direct sun for most of the day until mid afternoon. I am really surprised that the fish are still alive and that the racoons have not discovered it yet! Will try to post images in a day or so.

I'm so glad I'm in the area where raccoons don't exist!

I read about that Windmill pond aeration system before, too. I think the solar power pond aeration system is more suitable because it's more reliable than the wind power. I totally agree with you, I wish they could produce a smaller system.

I'm looking forward to see those images!

Yeah, I never even imagined having racoons here. I am at least a mile and a half away from anywhere that there could even be racoons! Possums are common too but really no bother for the pools.
Here are a couple of images. One of the pool before some surface cleaning and one after. Still cannot believe the Rosy Reds survive there!!
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That looks very nice, and the water is so clear! For me, I'm not surprise your Rosy Red survive in there. I also like how the Sagittaria species took over the bottom pond, it's like a grassy miniature meadow on the bottom of the pond water.

I want to add Myriophyllum aquaticum in my tank, like what you have in that pond, which was available at my local fish store before--now most of my local fish store close to my area where they also sells aquatic plants are out of business, some pet store discontinued selling fishes and aquatic plants altogether, and this is within 2 or 3 years time frame. Very unfortunate.

I want to have a pond like yours, but bigger, however I can't because I have a toddler nephew running around and afraid of him drowning, and my dogs probably would take a bath in it.

Thanks for the comments.
I have plenty of the Parrots Feather if you want some no problem. Let me know.
Having a toddler can pose all kinds of problems for any body of water, even just 3 or 4 inches deep. I will not recommend any kind of fencing but for such small pools as these the best security would be a hard wire mesh cover that could be securely mounted or make a boxlike enclosure for a free standing pool that could handle having sand poured in around the pool between the box walls and the pool (presuming preformed) walls and then make a cover using a frame with the hardware cloth mounted so that it could not be torn off even by a large animal and attach securely to the box with a set of hinges on one side and a padlock on the other so that one could open it up to clean or add plants. You could even let plants grow through the hardware cloth cover but they would have to be clipped down if you need to open it unless they were small plants like Acorus. This kind of set up would keep out any animal.
You should probably make your aquariums safe as well.
And I would recommend enrolling your toddler in a swimming class as toddlers can take to water very easily. Check the link below.

Here is a link that might be useful: Teach your little one to swim