>Green water and soft water? I have the hardest water ever in my 55g , and 22 g high , and 6g , and a 100 g pond tank on the deck. The deck one will get green water in two days if I don`t have it coveredor planted . Once it warms up , I`ll add some plants and that will keep it at bay a bit longer, but it`s still a challenge. so, yes , you can have green water with very hard water. DT