The tank is still young, as time goes by this will happen less and less. The spring population will eventually rise up to a point where it can keep the mold in check. Adding more springs may help, but as long as there is air movement and water isnt just sitting on the plants, this will pass.It's been set up for just over 40 days now. I added some ABG mix to this vivarium from a different tank that I seeded with springtails, so there are some springtails. Do you thinking adding more or a second species would help?