Wolf I don't change out my Eco-earth I just add a fresh layer every 4-6 weeks and it will decompose under the new layer and eventually turn into new compost/dirt. One of my oldest terrestrial tanks is 4 years old and my substrate level is now about 5 inches thick, but I don now have live plants thriving in it from all of the old fecal matter that turned into organic fertilizer! As far as the frog moss I rinse mine out every 4-6 weeks as well when I add a new substrate layer. This helps remove fecal material and I get a longer life out of it, however I would replace it fully at least 3 times a year as it will start to decompose and may have a rotten vegetable smell sometimes like rotten eggs after three months even when you rinse it out once a month.