I should also add that I fill all my aquatic vases with old tank water, so there are some nitrates present for the plants to use. I also always add something animalia to each vase and feed tiny amounts of crushed fish food once in a blue moon. Usually scuds or daphnia, sometimes water mites or worms, nematodes or even mini ramshorn snails. They all work fine and poo for the plants. Extremely low maintenance, these populations stabilize themselves and require almost no attention at all. Actually, less is better most of the time.