Using willow method can also pose a challenge because you will need to find the tree itself. Once you come across one, pluck a few branches with the leaves intact and then place it in your fish tank. Somehow based on my own experience, using just the willow method itself may not be sufficient to quickly clear off the green water problem and as such you can do it along with introduction of daphnia to the water. Daphnia can be easily bought in any aquarium pet stores and the food for these planktonic crustaceans are actually algae. However, before you put in the daphnia, make sure that the aquarium fish has to be removed to another backup tank, or else the daphnia will end up as food for your pets. Together with the willow method this will help to clear up the aquarium green water problem much faster.
Using willow method is more like applying corrective action rather than preventing the whole problem before it actually gets out of hand. In fact, it is only effective during the early stage when you first spotted the aquarium water starts to turn slightly greenish. Somehow, it will be quite useless to apply the method when algae bloom has already developed to the advanced stage and as such I always believe the whole mess can be avoided if you follow some simple methods as mentioned earlier in the aquarium algae control topic.