The specific method for putting water in a tank depends on the size of the tank, the source of the water, and the desired level of precision and control. Here's one example method:
Fill a 5-gallon bucket, then use a pitcher to dip into the bucket and pour it into the tank. This allows for slow and controlled pouring, minimizing disturbance to plants and the substrate. Refill the tank in increments of 5-10 gallons at a time.
This is just one way to do it. There are several other possibilities depending on the type of tank.
