This may help: I have two small fresh-water aquariums and change out water (~1 gallon for 2 tanks) twice a week. I save aside the water to soak my Tillandsias in weekly and also to fill a spray bottle to spray the plants once or twice daily due to our natural low humidity. I have a lot of real plants in both aquariums, but I'm sure they don't use all the fish and snail poop and urine (and I rarely add any aquarium plant fertilizer), so the Tillandsias can have some diluted "fish droppings" as well. After the Tillandsias have their bath, I pour that water on my regular house plants. I have used this system for over a year now and all the plants seem satisfied.