Been using for 3 years and never had a problem
I use half a pack, soak the grains/medium for 24hours and then place them in a Cattit tray - it is eaten by three cats and two small dogs and they make a mess unless grown in this container. It ALWAYS grows, never had a problem. But you need to water sparingly daily, turn it round and round then drain completely immediately afterwards, takes less than 30secs daily. If you drain thoroughly you don't get mould. If you don't, you get problems. End of.