I have acquired a tank and older fleck softener head. I would like to turn the tank into a iron/sulfide AIO filter. Tank size is 10x40. When looking for a used head which ones are good for AIO? I have heard fleck 2510, clack ws1. With these heads is there any way to tell if it is configured for a softener or filter? Is it difficult to modify to a AIO system if I end up with one that was a softener head previously? Thinking I am going with a katalox lite system.