I can't give you an answer. I grow both species of plants in my small outdoor ponds and have no trouble with them. The water hyacinth dies when the water freezes in the winter and has to be replaced when the weather warms up, but the water lettuce comes back on its own in the spring.
I have heard they are difficult to maintain in containers, such as aquariums. I investigated keeping a few plants over the winter indoors in an aquarium, but everything I read and everyone I spoke with advised me that it was quite difficult to do. They are actually "pond weeds" here where I live, and I've discovered that it's easy to find people giving them away.
I have no idea what type of container you're growing the plants in, but I sure wouldn't recommend adding any kind of manure to the water. If the container is big enough to support fish, you might add some of them. Their excreta might be sufficient to feed the plants. That's the only suggestion I have. My ponds have no fish, but frogs and other wild amphibians visit often.
If yours is a hydroponics or aquaponics system, I can move your question to our [url=https://www.helpfulgardener.com/forum/viewforum.php?f=42]Hydroponics forum[/url], if you like. You might get a good answer there.
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams