You have to see something here. PWC
`s accomplish many things. Two main things they do are 1) They replenish trace elements that get used up during fish and coral processes. These trace elements are found in marine salt mix that you do PWC
`s. 2) They dilute excessive nutrients in your tank that causes nuisance algea and poor fish and coral health in your tank. PWC
`s are very important in a SW
tank. Your friends advice about never doing them is not wise. I`ve done weekly PWC
`s for 11 yrs now and I`m glad I did and will continue to do so.