Kenmore Model: 625.3484400, serial 15782: The home has hard water with iron in it. I think my manual said that I am to use the large pellet salt rocks, and not the little tiny ones. I also think that it distictly said to "NOT'" use the salt that has iron reducing products in the pellets because it would eventually hurt the tank & mechanisms that run the softner. I cannot find the manual, and I cannot find it online anymore. I have an older model which still seems to work well, so I don't want to put the wrong stuff in it now. It is a rental, and we just changed tenants, who purchased the smaller rocks, not knowing which to buy. I think, if I am correct in what the manual says, we need to change those pellets, or use them up, and begin purchasing the correct size and type. Am I correct in thinking that is what the manual says? Does anyone have that manual? Thanks