I wouldn't clean my decorations every week. You need to allow for the beneficial bacteria to grow in your tank, and it grows on your decorations as well as your gravel and in your filter. If you're constantly cleaning your decorations, then you're killing off that bacteria. Does that make sense?

If you're concerned about algae growth, you can see about getting a couple otos or a pleco (depending on your tank size). But, you do need to let that bacteria grow. I wouldn't do as much cleaning until you know for sure what's going on with your goldfish. Water changes are great - definitely do those!