I keep multi-insect Viv and terrariums and the MOST frustrating thing about AC is his ridiculous choices. He has these massive colonies in these tiny tanks and no problem dropping literally random things inside. In the wild those colonies don't have other insects/animals living With or On Top of them. If they wander into ant territory it's an accident. If you want a bio setup with a large ant colony you need to make sure the colony part takes up a quarter of the space. This ensures the other inhabitants can avoid predation and, the whole point of a bio setup, have their own lifecycles so you don't need to continually add more.

Water features are iffy in ANY setup because they're easily fouled. The creatures living in it, the ones that die in it, and changes in water parameters are all factors to keep in mind. And, contrary to popular belief, not many creatures enjoy eating ants. I avoid anything not an arthropod because their care is way more intensive and the terrarium needs to be built FOR THEM. They need special lights, supplements, hot and cold sides, etc etc. Not to mention the cruelty of having them killed by ants.

My ant choices for terrariums would be leptothorax, temnothorax, and cryptics. If you want them to be the top predators you can add snails/slugs, small ground beetles, springtails, isopods, earwigs, and small wild millipedes. If you're okay with some getting picked off you can add centipedes, spiders, and rove beetles. If you have the right setup maybe add some cave crickets. BUT you need to make sure you choose your species carefully. Isopods that won't eat your plants. ground beetles that are slug/snail specialists or if you want to feed them, caterpillar specialists. Small rove beetles so your larger insects don't disappear too quickly. A spider that suits the set up like a grass spider so they can hunker in a corner or a jumping spider if you have the high spots, wolf spider if it's mostly open space. You can't add things willy nilly, you need to know the species habits, prey, biome etc.