Since my last post on this tank, nearly 10 days ago, I have been fearful of a high ammonia or nitrite reading again. However, the tank is beginning to mature well. Today, I cleaned the canister filter and vacuumed 20 gallons from the rock at the bottom of the tank. Anyone who has kept koi in a tank knows that rock is not the best idea in the world. However, the fish seemed to enjoy the cleaner water and are continuing to thrive. Of course, these koi are not growing as fast as the koi in the office pond. The koi in this tank are fed only once per day, on average, because I am not home often enough to feed them more regularly and the kids cannot reach the opening at the top of the tank. Slow growth is quite acceptable; however, as I have not done much with my plans for the outdoor pond in which they will live out their adult years.