So I clean out about 50% once a week. I hook a garden hose up that I start a siphon on and drain out my window into some plant beds. While the water is draining I siphon the gravel and take out about 20 gallons of water in buckets. When that is done I hook the hose up to the faucet and refill the tank with a very slow dribble. Adding chemicals to remove chlorine/adjust pH as it fills and adding warmer water with a bucket if needed.