So all you guys that have custom indoor ponds, built in 1000+ gallon tanks. What do you do for water change and how often do you do them? I'm looking at doing a in wall build for my rays and piggy that system's filtration and water on a 12'x30"x24" piranha tank. I was just wondering what to do and how you guys do tank maintenance. Since there is so much more water do you not have to do changes as often, are they more self sustaining then a regular in home tank? Any info you guys have as to how you take care of your set up, how often things need done and some things to look out for before I dive into this.