Review on AQQA 6-in-1 Electric Aquarium Gravel Cleaner and Vacuum - Automatic Fish Tank Cleaning Tools, suitable for Water Change, Sand Washing, Filter Maintenance, and Circulation (320GPH, 20W) by Robert Patton

Highly Recommended! I have a 20 gallon (tall) aquarium with over 30 guppies. I use sand and lava rocks as substrate so I have to change the water to clean the substrate at least twice a week. This gravel cleaner has different attachments that fit anywhere in my tank. You can choose the bait based on the size of your fish, your aquarium and your substrate. I find this extremely helpful when adding water to a tank. Very happy with this purchase!