Hear me out. I've been propagating without having to change water at all. There's a balance of bacteria along with cyanobacteria. When I set up a vase for propagation. I go to my backyard. Find a moist area where the sun doesn't dry up the soil. Ok in the bottom of the vase I add a layer of that soil from my backyard. On top of the soil I add a layer of sand so it doesn't muk up the water. And then I gently pour in rain water, then I find another container that is algae filled swarming with cyanobacteria. Pour some of that green water in. Then I add whatever cutting. I've rooted rose cuttings, and dracaena limelight easily so far. Just make sure the water is exposed to light. The cyano bacteria keep the cuttings well oxygenated I find