I am thinking of setting up a second salt water tank specifically for urchins and other creatures that I cannot keep in my reef tank. I was going to take one of my tanks that I had previously used as fresh water and just use all of the equipment I already have for the tank. Will using a HOB filter system be ok to use for this type of set up? I really do not want to get all new equipment unless it is absolutely a must. Ideas and suggestions are very welcome.