Our methods are cheap and easy, and require little supervision.
We have coined the name, THE TOTEM POLE METHOD
You need a container large enough for your new pet to fit in comfortably. The container must have an overflow.
A food dish with a small overflow tube shoved through it will be just fine, as long as the fish cannot swim through it. set a bucket under the acclimation container that can handle 3x the volume of water Your container will hold. The 3 levels of containers (fishtank>Acclimation container>Waste Bucket) resemble a totem pole.
Take an air hose from what ever water source you are acclimating to and siphon the water from that into the container. Tie a not or pinch the hose so that it drips rather than pours. This ensures that the water chemistry will slowly change and not shock your creature.
After the bucket on the floor has about 3x the water of your container, you should be ready to add them to the tank. This method can be used for any size container as long as you have enough water to replace in your Fishtank. (Good time for a water change while your at it).
If you are using a larger container, an air bubbler may Be used to agitate the surface for gas exchange and prevents detritus from building up during long acclimations for mollies or any other fresh/salt procedures. You can actually link as many containers as you want and with some ingenuity make some very Nice setups. Only link containers if each life form you are acclimating is from the same water. If you buy from separate stores or even separate systems in the same store, it is not advisable to mix the water. However, if you hook up 2 acclimation containers of different water, you may drain them into the same waste bucket.
And remember, ALWAYS QUARANTINE EVERYTHING.