Hi so I have a cycled aquarium that is inhabited atm but in a few weeks I expect to restock it. Right now it has 2 large rocks and a small house like thing. I'm wondering if it would mess up the cycle if I was to take these decorations out and put new ones in. Also I need some advice on decoration choices. I have blue, black and red gravel and I would like to go for a more natural look (not bright colours) without replacing the gravel. Any ideas on colours that would look nice I know the gravel might contrast a lot of decorations but I'm open to ideas. The aquarium is 20 gallons.