I'm at the one year mark with my first Marine aquarium (20 gallon AIO). The sand substrate is 25% Caribsea Bahamas Oolite, 75% Caribsea Fiji Pink sand. After about 10 months the sand looks perpetually "dirty", no longer white new tank look. I vacuum the top layer and/or do a full sand bed vacuum every 3-4 weeks during water changes. The sand bed just seems to look darker and dirtier over time despite good cleaning. I use the small diameter Python Pro Clean gravel vacuum. Inhabitants are 1 lawnmower blenny, 1 clown fish, 1 saltwater molly, 1 cleaner shrimp, 1 fighter conch snail, 3 bumble bee snails, 5 or 6 blue leg hermit crabs, 1 other small snail. Good amount of coral in the tank. I am upgrading to 50 gallon in a week and am hoping there is sand that still looks good at a year? Or is that a pipe dream. I don't plan on having sand sifting starfish or goibies for small diameter grain sand. I live in apartment and rinsing dry sand will be difficult task. Any experience with sand looking dirty over the moths? Any experiences with sand that still looks good over the months? Thank you!