Due to the need to really keep the carnivorous plants with as low tds water as possible, I would segregate them from everything else in the tank. Meaning I would build my hardscape into a raised area that is not submersed in the waterfall at all and instead plan to water them completely separately. That will allow you to whatever you want with the rest of the plants in the tank. Alternatively you could make this a carnivorous plant only tank. I know there are pitcher plants sold as marginal pond plants. They get pretty big so they might overwhelm your tank though.

 

Keep in mind that I have limited knowledge of a lot of the varieties of the carnivorous plants, and I also don't know which ones you are planning on getting. That being said, a lot of the types like to have a period of dormancy. I've raised venus flytraps without giving them a dormant period, and they seemed to do well. Unfortunately I left them outside one summer evening and something dug up the whole pot and killed them all. This prevented me from a long term run to say for sure one way or the other about the dormancy period for them. I know some others here have kept them, I can't remember who but hopefully they can comment on that. I'd hate so see you pull them out of a carefully constructed hardscape.

 

I currently have a paludarium with both aquatic plants and carnivorous plants, and I respectfully disagree with both of the above posts. Your biggest issues will be keeping your bog area from being too saturated for most of the carnivorous plants you want to grow, and finding the right light levels for carnivorous plants and also Buces.

First of all, it’s quite easy to use distilled or R/O water and keep your ppm of TDS under 100 (aim for 50), which is fine for most carnivorous plants and also fine for a whole list of other aquatic plants that I can give you and that grow for me. Bornean peat swamp plants (which some Crypts are) are used to very pure water and low pH.

Second, only temperate carnivorous plants need dormancies, and I just read an argument that VFTs don’t need dormancies given the right care (but they are certainly temperate). Some Pings and sundews are temperate, along with all Sarracenias, but there are many, many tropical carnivorous plants.

Pure live sphagnum isn’t the best substrate, it grows pretty fast and can choke out/bury smaller plants, and I’m assuming based on your dimensions that you’ll want smaller plants. Dead sphagnum doesn’t do well completely saturated (been there, done that) so scrap the sphagnum. A typical carnivorous soil like 50/50 sand and peat will wick enough water up that some plants will be too wet, unless you can get it 3-4” deep. I have a 12x12” dish with a tiny water area that uses an equivalent to Matala (filter material that doesn’t wick water) as the underwater structure, and then sand/peat on top of that, and it’s working so far. You could put plants that like to be very wet, like most Utrics, at the water’s edge, and other plants like Droseras, Pings and Cephalotus further back where the soil is higher and less wet. Nepenthes is one that would be difficult in this setup, and too large anyway. You can also use large lava rocks sticking up out of the water, they wick just a little and Pings grow great on them.

This gets a little more complicated if you want something like shrimp living in your aquatic section, then you’ll need to remineralize your water right up to 150 TDS, however I am also successfully doing that. All of this is totally doable with some experimentation. I can give you more specific plant species suggestions if you’d like.

Here’s the Pinguicula rock in my paludarium, the base sits in about 1/2” of water and wicks from my 7 gallon aquatic section, which has cherry shrimp and lots of aquatic plants. I cannot keep Droseras in this tank, only because they hate the overhead misting system. I have Pinguicula agnata and cyclosecta on this rock, and they’ve at least doubled in size since the first pic:

You can see full tank shots of my paludarium if you follow the link in my signature.

 

I agree the Nepenthes would be way to big for that setup. I have one and the pitchers alone are hitting 3" and it's more than tripled in size in a few months. I'm growing it under a ONF Flat Nano at full power. Incredible insect catcher, I didn't even know I had ants until I got this plant. They go right to it, get stuck and eventually drowned. My wife is afraid of it, LOL.

 

Thanks for all the ideas. I wanted to update the thread with the result.
Unfortunately I gave up on the idea, because it became too complex for such a small paludarium (and my abilities).
I ended up replacing the carnivorous idea with two tiny species of orchids.

I put some moss, but it is indeed too tall and will outgrow the orchids, so I might remove it soon.
The bog area looks properly watered for now - the water moves very slowly ove there.

I'll wait and see how this goes. If an orchid dies I will try to put some small carnivorous plant in its place. I put them in separate holders so they can have a different substrate. There are holes at the bottom to get the water there.

I was not prepared for so much effort for something this small 😁
It was worth it, though

 

What is the substrate for the orchids? I think Pinguiculas would do better in those pots than either of those orchids, which I suspect will rot, but it depends somewhat on the substrate.

 

From the bottom to the water line there is gravel. Then on top of that there is some JBL Manado aquarium substrate, which remains moist. Then on top of that is the typical orchid substrate with some tree bark inside.

Do you think that a carnivorous plant can live in this configuration, sharing the same water with the other plants?