I know there are some back and forth about refugium mud. Do you have to change the refugium mud a lot, or is it best to do sand? and what type of sand is best for the refugium if thats the choice? The way they make the mud sound is like it slowly releases the trace elements and absorb all bad things in your water like nitrates, metals, and phosphates. what is your take on this. I greatly appreciate your thoughts on this and thanks for the help in advance.