Question

Tanks are decreasing . Why?

Answer 1

Explanation:

t’s shocking how quickly the warm water of an aquarium will evaporate in a dry room. When I had my big tank with an exhaust system in the canopy to deal with the heat from the lights, I would go through over a gallon of top off water a day.

Just remember that it's only the water that's evaporating. Everything else dissolved in that water (bad stuff like nitrates, phosphates, and salts) are just getting concentrated. If all you ever do is replace the evaporated water, you’ll eventually start having trouble keeping things alive for very long.