Substrate is important for our health cat, because it has to encourage you to make its needs when it wants, with no bad experiences. Ideally, that doesn't produce dust, no chemicals contain and doesn't have a strong odor that might bother our cat and shun of using. Furthermore, it should be comfortable for owner so it's also easy to clean and neutralize odors. It's advisable to clean tray daily to detect any problems that may have and to avoid health problems.