Quote Originally Posted by deranged chipmunk View Post
Yet another way is to water with waste aquarium water, which just made a whole bunch of people in here gasp in horror lol the fish waste in the water of a properly cycled tank will be super rich in n-p-k.

There is one last option that I won't mention here because I don't need anyone's head exploding lol...
The aquarium water removed from a healthy tank will work fine as long as there is no salt added to it. Many an aquarist will add salt to tank (around 2 TBS per 5 gal.) and that salt will create a progressive buildup in substrate until it affects plants.

OK Bill, promise my head won't explode, what is the secret method ?