Currently I have obnoxiously colored gravel in my 7gal that I want to switch to sand. I set the tank up a long time ago and have never done a complete gravel change, since I'm guessing that could impact the cycling. So I've just always done syphoning. Now, I hate the look of the colored gravel, my fish probably hates the colored gravel, and we both want it changed lol. How can I do this safely without affecting my cycle or doing a 100% water change if that's possible?