Many of your plants grow fast. And that may be evolutionary due to their inherent deliciousness.
So you providing semi-vegetarians with the best greens they could hope for.
Try slower growing plants as mentioned.
I have had luck with many slower plants except in my leporinus tank as they will eat/shred anubius, pothos roots and all else sometimes seemingly just for the hell of it.
Val has worked for me for a short time and then just seems to peter out.
I am experimenting with growing potted aquarium plants. When they get big and need a trim, I pop them in the veg eating tanks and let them get a "natural buzz cut" then remove and regrow as a source of "live" food. This is where the sump
duanes
mentioned is an asset surpassing it's price. It also allows unrestricted growth on emersed plants to soak up nutrients.
This is when they were first planted and started growing. Cabomba should renamed to The Bomba. Grpows fast. In low or bright light. Floating, planted. In a sump, in a tank in a bowl.
You could also add smaller air Driven "refugiums" on your tanks wher plants grow. When crowded, trim and drop into tank for fish to munch on. Or sponge off an area to protect plants.