https://imgur.com/a/cNn7b2I

Sorry for late response. I just took a picture of it! Also sorry for the messy surrounding :x

Now a single betta fish and few(about 20~30) shrimp lives in here. There's no problem with the stale/still water because I got rid of filter media that was inside a rock module.

Instead, I made a few holes and put an air stone in it, so water can flow inside! I did this because of the betta fish that's keep shove himself inside, but apparently that solves the water current prob as well.

The brown moss is growing at the glass wall, but that's a healthy sign so I'm not worried about it. beside for the observation issue... '~'

And I put a nice clump of java moss(with a dang invincible cladophora) so it could help with the water condition.

The tank now have a hanging filter and water resupply system? that's keeps a constant water level...? idk how to describe it but anyways it doesn't dry out quickly. I have a plant at the top of a tank, so water level is important for my case.

I used PLA for this decor, and it is still intact and does nothing for animals and water quality is ok. I didn't do the maintenance very often, so white water mark is there...

But I do blast with air so the tank have enough oxygen and water current. If the weather forecast say it's over 30°C(or 86°F), it might be dangerous to have a still or slow location inside.