My top off is crazy.. back in the day I dont remember my tank evaporating that much. The 180 was in The house and the sump in the garage ,.. Now I am close to 1.5 g a day with 1/4 size of the system.. but I will admit I really didnt pay that much attention to it.Is it the water change or the maintenance that goes with it. I just did a 20 on an 80 g system.... as type this .. there is something.. like it has no flow..