Some fish, and particularly fry and marine fish need to have new water added slowly to avoid temperture and or chemical shock. Here are 2 ways I've found and used to accomplish this goal.
1. Get a plastic container such as a microwave dish or a shoe box and punch one or two tiny holes in it. You can prop it on the corner of the tank with the holes directed into the tank water, then fill it with the new water and let it slowly flow into the aquarium, meantime you can be doing other chores.
Here you can see the water changing method number 2 being done, notice the airline hose running from the jug up top into a 5 gallon tank.
2. Use your normal water changing bucket and use some airline tubing and a airline valve to make a slow flowing hose for your change water. I use this method to make all my water changes, I can adjust the valve to make it as slow or fast as I need, and I have it long enough to reach all the tanks from one place. I can be scraping algae and cleaning out one tank while another is filling. It's one of my most handy tools.
Anything you can do to make water changes easier and less troublesome is great because if it's not as big a chore then you'll likely do it more often, and folks, the truth is, a water change every day wouldn't hurt a thing.
