The Innovative Marine Hydrofill Ti reservoir is quite amazing. Don't know where it has been for all of my life, but considering they literally JUST came out with it - where has this concept been all of my life? My cabinet doesn't have room to fit this and still be able to open the drawer to fill, so I had to put it beside the tank. If you've read the article I wrote for Marine Depot just before they were released, you know that cool drawer system for filling the water. This is 5 gallons and my largest ATO reservoir in history. I can see for myself how cool this concept is. Wonder if they are coming out with a bigger reservoir with the same concept for folks like @veng that like more water. But considering how simple and easy it is to refill, with the ability to fit it inside the cabinet, it should suffice for most smaller systems.