two of my most favorite echino are having a little receding. i dont know why it receding but i am very worry one of them is a watermelon chalice and i paid goood money for it. all water are tested stable. the only thing new i can think of is a new fan for the light, and the fan makes the water cold so the temperature is kinda low in the process of getting new heater. dont know if that could be an issues. thanks in advance for all the help.